Hostname: page-component-78c5997874-g7gxr Total loading time: 0 Render date: 2024-11-08T01:28:19.438Z Has data issue: false hasContentIssue false
  • English
  • Français

Fetal cardiovascular reflex responses to hypoxaemia

Published online by Cambridge University Press:  10 October 2008

Dino A Giussani ,
John AD Spencer  and
Mark A Hanson
Dino A Giussani*
Affiliation:
University of College Medical School, London, UK.
John AD Spencer
Affiliation:
University of College Medical School, London, UK.
Mark A Hanson
Affiliation:
University of College Medical School, London, UK.
*
Dr DA Giussani, Department of Obstetrics and Gynaecology, University College Medical School, 86–96 Chenies Mews, LondonWC1E 6HX.
Get access Rights & Permissions [Opens in a new window]

Extract

The fetus mounts a coordinated cardiovascular response to an insult of acute hypoxaemia which involves neural and endocrine components. During acute hypoxaemia in late pregnancy there is a transient bradycardia, a gradual increase in arterial blood pressure and an increase in heart rate variability. In addition, there is a redistribution of the combined ventricular output favouring the cerebral, myocardial and adrenal circulations by shunting blood away from the peripheral circulations. A component of the increase in peripheral vascular resistance and the increase in arterial blood pressure during acute hypoxaemia is mediated via increases in plasma concentrations of vasoconstrictor hormones such as vasopressin, angiotensin II and neuropeptide Y. Whilst an increase in plasma ACTH and cortisol is also seen during acute hypoxaemia, their contribution to cardiovascular control in fetal sheep is less clear.

Evidence has been presented to suggest that a number of these cardiovascular and endocrine responses to acute hypoxaemia are chemorefiex in nature, mediated principally by carotid chemoreceptor afferents. In addition, this reflex may be modifiable in terms of changes in magnitude and gain: first, by an influence of the intrauterine environment during chronic hypoxaemia and second, through genetic influences, in animals adapted to life at high altitude.

Type
Articles
Information
Fetal and Maternal Medicine Review , Volume 6 , Issue 1 , February 1994 , pp. 17 - 37
Copyright
Copyright © Cambridge University Press 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1Villar, J, Smeriglio, V, Martorell, R, Brown, CH, Klein, RE. Heterogenous growth and mental development of intrauterine growth-retarded infants during the first 3 years of life. Pediatrics 1984; 74: 783–91.CrossRefGoogle ScholarPubMed
2Taylor, DJ. Neurological sequelae of intrauterine deprivation. In: Spencer, JAD ed. Fetal monitoring. Oxford: Oxford University Press, 1991: 20–23.Google Scholar
3Borell, U, Fernstrom, I, Ohlson, L, Wiqvist, N. Influence of uterine contractions on the uteroplacental blood flow at term. Am J Obstet Gynecol 1965; 93: 44–57.CrossRefGoogle ScholarPubMed
4Schwarcz, RL, Belizan, JM, Cifuentes, JR, Cuadro, JC, Marques, MB, Caldeyro-Barcia, R. Fetal and maternal monitoring in spontaneous labors and in elective inductions. Am J Obstet Gynecol 1974; 120: 356–62.CrossRefGoogle ScholarPubMed
5DeVries, JIP, Visser, GHA, Prechtl, HFR. The emergence of fetal behaviour. i)Qualitative aspects. Early Hum Dev 1982; 5: 87–94.Google Scholar
6Nijhuis, JG. Fetal behavioural states. In: Spencer, JAD ed. Fetal monitoring: physiology and techniques of antenatal and intrapartum assessment. Oxford: Oxford University Press, 1991: 24–27.Google Scholar
7Nijhuis, JG, Tas, BAPJ. Physiological and clinical aspects of the development of fetal behaviour. In: Hanson, MA ed. The fetal and neonatal brainstem: developmental and clinical issues. Cambridge: Cambridge University Press, 1992: 268–80.Google Scholar
8Spencer, JAD. Fetal responses to labour. Proceedings of 26th Study Group of the RCOG; Intra-partum fetal surveillance. London: Royal College of Obstetricians and Gynaecologists, 1993: (in press).Google Scholar
9Ingemarsson, I, Ingemarsson, E, Spencer, JAD. Fetal heart monitoring. A practical guide. Oxford: Oxford University Press, 1992: 125–81.Google Scholar
10McCrann, S, Schifrin, BS. Fetal monitoring in high-risk pregnancy. Clin Perinatcal 1974; 1: 149–55.Google ScholarPubMed
11Peebles, DM, Spencer, JAD, Edwards, AD, Wyatt, JS, Reynolds, EOR. Relation between frequency of uterine contractions and human fetal cerebral oxygen saturation studied during labour by near infrared spectroscopy. Br J Obstet Gynaecol 1994 (in press).CrossRefGoogle ScholarPubMed
12Campbell, S, Diaz-Recasens, J, Griffin, DR, Cohen-Overbeek, TE, Pearce, JM, Wilson, K et al. New Doppler technique for assessing utero-placental blood flow. Lancet 1983; 1: 657–59.Google Scholar
13Griffin, D, Bilardo, K, Masini, L, Diaz-Recasens, J, Pearce, M, Wilson, K et al. Doppler blood flow waveforms in the descending aorta of the human fetus. Br J Obstet Gynaecol 1984; 91: 997–1006.CrossRefGoogle ScholarPubMed
14Wladimiroff, JW, Tonge, HM, Stewart, PA. Doppler ultrasound assessment of cerebral blood flow in the human fetus. Br J Obstet Gynaecol 1986; 93: 471–75.CrossRefGoogle ScholarPubMed
15Stewart, PA, Wladimiroff, JW, Stijnen, T. Blood flow velocity waveforms from the fetal external iliac artery as a measure of lower extremity vascular resistance. Br J Obstet Gynaecol 1990; 97; 425–30.CrossRefGoogle ScholarPubMed
16Mari, G. Arterial blood flow velocity waveforms of the pelvis and lower extremities in normal and growth-retarded fetuses. Am J Obstet Gynecol 1991; 165; 143–51.CrossRefGoogle ScholarPubMed
17Akalin-Sel, T, Campbell, S. Understanding the pathophysiology of intrauterine growth retardation: the role of the ‘lower limb reflex’ in redistribution of blood flow. Eur J Obstet Gynecol Reprod Biol 1992; 46: 79–86.CrossRefGoogle ScholarPubMed
18Nicolaides, KH, Economides, DL, Soothill, PW. Blood gases, pH, and lactate in appropriate-and small-for-gestational-age fetuses. Am J Obstet Gynecol 1989; 161: 996–1001.CrossRefGoogle ScholarPubMed
19Bilardo, CM, Nicolaides, KH, Campbell, S. Doppler measurements of fetal and uteroplacental circulations: relationship with umbilical venous blood gases measured at cordocentesis. Am J Obstet Gynecol 1990; 162: 115–120.CrossRefGoogle ScholarPubMed
20Nijhuis, JG, Bots, RSGM, Martin, CBJR, Prechtl, HFR. Are there behavioural states in the human fetus?. Early Hum Dev 1982; 6: 177–95.CrossRefGoogle ScholarPubMed
21Prechtl, HF. The behavioural states of the newborn infant (a review). Brain Res 1974; 76: 185–212.CrossRefGoogle ScholarPubMed
22Spencer, JAD. Use of the Vasoflo-3 for continues wave Doppler ultrasound measurements in pregnancy. Fetal Med Rev 1989; 1: 105–10.CrossRefGoogle Scholar
23Spencer, JAD, Giussani, DA, Moore, PJ, Hanson, MA. In vitro validation of Doppler indices using blood and water. J Ultrasound Med 1991; 10: 305–308.CrossRefGoogle ScholarPubMed
24Giussani, DA, Moore, PJ, Spencer, JAD, Hanson, MA. Changes in compliance affect PI at constant flow in an in vitro flow model. J Mat Fetal Invest 1992; 2(2): 123.Google Scholar
25Giussani, DA, Moore, PJ, Spencer, JAD, Hanson, MA. Modelling the effect of changes in compliance on Doppler flow-velocity waveforms. J Mat Fetal Invest 1992; 2(2): 124.Google Scholar
26Meschia, G, Cotter, JR, Breathnach, CS, Barron, DH. The haemoglobin, oxygen, carbon dioxide, and hydrogen ion concentrations in the umbilical blood of fetal sheep and goats as sampled via indwelling plastic catheters. Q J Exp Physiol 1965; 50: 189–95.Google ScholarPubMed
27Duke, C, Fownes, D, Wade, JC. Halothane depresses baroreflex control of heart rate in man. Anesthesiology 1977; 46: 184–87.CrossRefGoogle ScholarPubMed
28Gregory, GA. The baroresponses of preterm infants during halothane anaesthesia. Can Anaesth Soc J 1982; 29: 105–108.CrossRefGoogle ScholarPubMed
29Wear, R, Robinson, S, Gregory, GA. Effect of halothane on the baroresponse of adult and baby rabbits. Anesthesiology 1982; 56: 188–91.CrossRefGoogle ScholarPubMed
30Mayer, N, Zimpfer, M, Raberger, G, Beck, A. Fentanyl inhibits the canine carotid chemoreceptor reflex. Anesth Analg 1989; 69: 756–62.CrossRefGoogle ScholarPubMed
31Beck, A, Zimpfer, M, Raberger, G. Inhibition of the carotid chemoreceptor reflex by enflurane in chronically instrumented dogs. Naunyn Schmiedebergs Arch Pharmacol 1982; 321: 145–48.CrossRefGoogle ScholarPubMed
32Zimpfer, M, Sit, SP, Vatner, SF. Effects of anaesthesia on canine carotid chemoreceptor reflex. Circ Res 1981; 48: 400–406.CrossRefGoogle ScholarPubMed
33Lumbers, ER, Lewes, JL. The actions of vasoactive drugs on fetal and maternal plasma renin activity. Biol Neonate 1979; 35: 23–32.CrossRefGoogle ScholarPubMed
34Rose, JC, Meis, PJ, Morris, M. Ontogeny of endocrine (ACTH, vasopressin, cortisol) responses to hypotension in lamb fetuses. Am J Physiol 1981; 240: E656–E661.Google ScholarPubMed
35Wood, CE. Sinoarotic denervation attenuates the reflex responses to hypotension in fetal sheep. Am J Physiol 1989; 256: R1103–R1110.Google Scholar
36Alexander, DP, Britton, HG, Forsling, ML, Nixon, DA, Ratcliffe, JG. Adrenocorticotrophin and vasopressin in foetal sheep and the response to stress. In: Pierrepoint, CG ed, The endocrinology of pregnancy and parturition. Cardiff, UK: Alpha Omega Alpha. 1973.Google Scholar
37Robillard, JE, Gomez, A, Meernick, JG, Keuhl, WD, Vanorden, D. Role of angiotensin II on the adrenal and vascular responses to hemorrhage during development in fetal lambs. Circ Res 1982; 50: 645–50.CrossRefGoogle ScholarPubMed
38Gu, W, Jones, CT, Parer, JT. Metabolic and cardiovascular effects on fetal sheep of sustained reduction of uterine blood flow. J Physiol 1985; 368: 109–29.CrossRefGoogle ScholarPubMed
39Yaffe, H, Parer, JT, Block, BS, Llanos, AJ. Cardiorespiratory responses to graded reductions of uterine blood flow in the sheep. J Dev Physiol 1987; 9: 325–36.Google ScholarPubMed
40Boyle, DW, Hirst, K, Zerbe, GO, Meschia, G, Wilkening, RB. Fetal hind limb oxygen consumption and blood flow during acute graded hypoxia. Ped Res 1990; 28: 94–100.CrossRefGoogle ScholarPubMed
41Dawes, GS, Lewis, BV, Milligan, JE, Roach, MR, Talner, NS. Vasomotor responses in the hind limbs of foetal and new born lambs to asphyxia and aortic chemoreceptor stimulation. J Physiol 1968; 195: 55–81.CrossRefGoogle ScholarPubMed
42Itskovitz, J, Lagamma, EF, Rudolph, AM. Effects of cord compression on fetal blood flow distribution and oxygen delivery. Am J Physiol 1987; 252: H100–H109.Google Scholar
43Fumia, FD, Edelstone, DI, Holzman, IR. Blood flow and oxygen delivery to fetal organs as function of fetal hematocrit. Am J Obstet Gynecol 1984; 150: 274–82.CrossRefGoogle ScholarPubMed
44Paulone, ME, Edelstone, DI, Shedd, A. Effects of maternal anemia on uteroplacental and fetal oxidative metabolism in sheep. Am J Obstet Gynecol 1987; 156: 230–36.CrossRefGoogle ScholarPubMed
45Battaglia, FC, Bowes, W, McGaughey, H, Makowski, EL, Meschia, G. The effect of fetal exchange transfusions with adult blood upon fetal oxygenation. Ped Res 1969; 3: 60–65.CrossRefGoogle ScholarPubMed
46Itskovitz, J, Goetzman, BW, Roman, C, Rudolph, AM. Effects of fetal-maternal exchange transfusion on fetal oxygenation and blood flow distribution. Am J Physiol 1984; 247: H655–H660.Google ScholarPubMed
47Boddy, K, Dawes, GS, Fisher, R, Pinter, S, Robinson, JS. Foetal respiratory movements, electrocortical and cardiovascular responses to hypoxemia and hypercapnia in sheep. J Physiol 1974; 243: 599–618.CrossRefGoogle ScholarPubMed
48Cohn, EH, Sacks, EJ, Heymann, MA, Rudolph, AM. Cardiovascular responses to hypoxemia and acidemia in fetal lambs. Am J Obstet Gynecol 1974; 120: 817–24.CrossRefGoogle ScholarPubMed
49Peeters, LLH, Sheldon, RE, Jones, MD, Makowski, EL, Meschia, G. Blood flow to fetal organs as a function of arterial oxygen content. Am J Obstet Gynecol 1979; 135: 637–46.CrossRefGoogle ScholarPubMed
50Reuss, ML, Parer, JT, Harris, JL, Kreuger, TR. Hemodynamic effects of alpha-adrenergic blockade during hypoxia in fetal sheep. Am J Obstet Gynecol 1982; 142: 410–15.CrossRefGoogle ScholarPubMed
51Rudolph, AM. Distribution and regulation of blood flow in the fetal and neonatal lamb. Circ Res 1985; 57: 811–21.CrossRefGoogle ScholarPubMed
52Jansen, AH, Belik, J, Ioffe, S, Chernick, V. Control of organ blood flow in fetal sheep during normoxia and hypoxia. Am J Physiol 1989; 257: H1132–H1139.Google ScholarPubMed
53Moore, PJ, Hanson, MA. The role of peripheral chemoreceptors in the rapid response of the pulmonary vasculature of the late gestation fetus to changes in PaO2. J Dev Physiol 1991; 16: 133–38.Google ScholarPubMed
54Paulick, RP, Meyers, RL, Rudolph, CD, Rudolph, AM. Hemodynamic responses to alpha-adrenergic blockade during hypoxemia in the fetal lamb. J Dev Physiol 1991; 16: 63–69.Google ScholarPubMed
55Jones, CT, Robinson, RO. Plasma catecholamines in fetal and adult sheep. J Physiol 1975; 248: 15–33.CrossRefGoogle ScholarPubMed
56Blanco, CE. Role of the brainstem in the changes at birth: initiation of continuous breathing and its maintenance. In: Hanson, MA ed, The fetal and neonatal brainstem: developmental and clinical issues. Cambridge: Cambridge University Press, 1991; 106–26.Google Scholar
57Kuipers, IM, Maetzdorf, WJ, Keunen, H, de Jong, DS, Hanson, MA, Blanco, CE. The effect of maternal hypoxemia on fetal behaviour in unanaesthetized normoxic or mildly hyperoxic fetal lambs. J Dev Physiol 1993; submitted.Google Scholar
58Dawes, GS. The central control of fetal breathing and skeletal muscle movements. J Physiol 1984; 346: 1–18.CrossRefGoogle ScholarPubMed
59Iwamoto, HS, Kaufman, T, Keil, LC, Rudolph, AM. Responses to acute hypoxemia in fetal sheep at 0.6–0.7 gestation. Am J Physiol 1989; 256: H613–H620.Google ScholarPubMed
60Dalton, KJ, Dawes, GS, Patrick, JE. Diurnal, respiratory and other rhythms of fetal lambs. Am J Obstet Gynecol 1977; 127: 414–24.CrossRefGoogle Scholar
61Parer, JT, Dijkstra, HR, Vredebregt, PPM, Harris, JL, Krueger, TR, Reuss, ML. Increased fetal heart rate variability with acute hypoxia in chronically instrumented sheep. Eur J Obstet Gynecol Reprod Biol 1980; 10: 393.CrossRefGoogle ScholarPubMed
62Longo, LD, Wyatt, JF, Hewitt, CW, Gilbert, RD. A comparison of circulatory responses to hypoxic hypoxia and carbon monoxide hypoxia in fetal blood flow and oxygenation. In: Longo, LD, Reneau, DD eds, Fetal and neonatal cardiovascular physiology. New York: Garland STPM Press, 1978.Google Scholar
63Itskovitz, J, Goetzman, BW, Rudolph, AM. Effects of hemorrhage on umbilical venous return and oxygen delivery in fetal lambs. Am J Physiol 1982; 242: H543–H548.Google ScholarPubMed
64Howard, RB, Hosokawa, T, Maguirre, MH. Hypoxic induced fetoplacental vasoconstriction in perfused human placental cotyledons. Am J Obstet Gynecol 1987; 157: 1261–66.CrossRefGoogle ScholarPubMed
65Jones, CT, Wei, G. Adrenal-medullary activity and cardiovascular control in the fetal sheep. In: Kunzel, W ed, Fetal heart rate monitoring. Berlin: Springer-Verlag, 1985: 127–35.CrossRefGoogle Scholar
66Rurak, DW. Plasma vasopressin levels during hypoxaemia and the cardiovascular effects of exogenous vasopressin in foetal and adult sheep. J Physiol 1978; 277: 341–57.CrossRefGoogle ScholarPubMed
67Daniel, SS, Stark, RI, Zubrow, AB, Fox, HE, Husain, MK, James, LS. Factors in the release of vasopressin by the hypoxic fetus. Endocrinology 1983; 113: 1623–28.CrossRefGoogle ScholarPubMed
68Piacquadio, KM, Brace, RA, Cheung, CY. Role of vasopresin in mediation of fetal cardiovascular responses to acute hypoxia. Am J Obstet Gynecol 1990; 163: 1294–1300.CrossRefGoogle Scholar
69Raff, H, Kane, CW, Wood, CE. Arginine vasopressin responses to hypoxia and hypercapnia in late-gestation fetal sheep. Am J Physiol 1991; 260 (Regulatory Integrative Comparative Physiology 29): R1077–R1081.Google ScholarPubMed
70Iwamoto, HS, Rudolph, AM, Keil, LC, Heymann, MA. Hemodynamic responses of the sheep fetus to vasopressin infusion. Circ Res 1979; 44: 430.CrossRefGoogle ScholarPubMed
71Pérez, R, Espinoza, M, Riquelme, R, Parer, JT, Llanos, AJ. Arginine vasopressin mediates cardiovascular responses to hypoxemia in fetal sheep. Am J Physiol 1989; 256: R1011–R1018.Google ScholarPubMed
72Broughton-Pipkin, F, Kirkpatrick, SML, Lumbers, ER, Mott, JC. Factors influencing plasma renin and angiotensin II in the conscious pregnant ewe and its foetus. J Physiol 1974; 243: 619–37.CrossRefGoogle ScholarPubMed
73Iwamoto, HS, Rudolph, AM. Effects of endogenous angiotensin II on the fetal circulation. J Dev Physiol 1979; 1: 283–93.Google ScholarPubMed
74Robillard, JE, Weitzman, RE, Burmeister, L, Smith, FG Jr. Developmental aspects of the renal response to hypoxemia in the lamb fetus. Circ Res 1981; 48: 128–38.CrossRefGoogle ScholarPubMed
75Wood, CE, Kane, C, Raff, H. Peripheral chemoreceptor control of fetal renin responses to hypoxia and hypercapnia. Circ Res 1990; 67: 722–32.CrossRefGoogle ScholarPubMed
76Scroop, GC, Marker, JD, Stankewytsch-Janusch, B, Seamark, RF. Angiotensin 1 and 2 and the assessment of baroreceptor function in fetal and neonatal sheep. J Dev Physiol 1986; 8: 123–38.Google ScholarPubMed
77Martin, AA, Kapoor, R, Scroop, GC. Hormonal factors in the control of heart rate in the normoxaemic and hypoxaemic fetal, neonatal and adult sheep. J Dev Physiol 1987; 9: 465–80.Google ScholarPubMed
78Iwamoto, HS, Rudolph, AM. Effects of angiotensin II on the blood flow and its distribution in fetal lambs. Circ Res 1981; 48: 183–89.CrossRefGoogle ScholarPubMed
79Jones, CT, Boddy, K, Robinson, JS, Ratcliffe, JG. Developmental changes in the response of the adrenal glands of the fetal sheep to endogenous corticotrophin, as indicated by hormone responses to hypoxaemia. J Endocrinol 1977; 72: 279–92.CrossRefGoogle ScholarPubMed
80Jones, CT, Roebuck, MM, Walker, DW, Johnston, BM. The role of the adrenal medulla and peripheral sympathetic nerves in the physiological responses of the fetal sheep to hypoxia. J Dev Physiol 1988; 10: 17–36.Google ScholarPubMed
81Akagi, K, Berdusco, ETM, Challis, JRG. Cortisol inhibits ACTH but not the AVP response to hypoxaemia in fetal lambs at days 123–128 of gestation. J Dev Physiol 1990; 14: 319–24.Google Scholar
82Tangalakis, K, Lumbers, ER, Moritz, KM, Towstoless, MK, Wintour, EM. Effect of cortisol on blood pressure and vascular reactivity in the ovine fetus. Exp Physiol 1992; 77: 709–17.CrossRefGoogle ScholarPubMed
83Walker, BR, Connacher, AA, Webb, DJ, Edwards, CR. Glucocorticoids and blood presure: a role for the cortisol/cortisone shuttle in the control of vascular tone in man. Clin Sci 1992; 83: 171–78.CrossRefGoogle Scholar
84Sanhueza, E, Carrasco, J, Gaete, F, Parraguez, V, Riquelme, R, Daniels, A et al. Neuropeptide Y (NPY) changes cardiac output and its distribution in the fetus. 28th Annual Meeting of the Latinamerican Society for Pediatric Research. Sao Paulo, Brazil, 1990: 61.Google Scholar
85Stark, RI, Wardlaw, SL, Daniel, SS, Sanocka, UM, James, LS, Van de Wiele, RL. Vasopressin secretion induced by hypoxia in sheep: developmental changes and relationship to β-endorphin release. Am J Obstet Gynecol 1982; 143: 204–12.CrossRefGoogle ScholarPubMed
86LaGamma, EF, Itskovitz, J, Rudolph, AM. Effects of naloxone on fetal circulatory responses to hypoxia. Am J Obstet Gynecol 1982; 143: 933.CrossRefGoogle Scholar
87Llanos, AJ, Court, DJ, Holbrook, H, Block, BS, Vega, R, Parer, JT. Cardiovascular effects of Naloxone (NLX) during asphyxia in fetal sheep. Soc Gynecol Invest Washington 1983: 300.Google Scholar
88Espinoza, M, Riquelme, R, Germain, AM, Tevah, J, Parer, JT, Llanos, AJ. Role of endogenous opioids in the cardiovascular responses to asphyxia in fetal sheep. Am J Physiol 1989; 256: R1063–R1068.Google ScholarPubMed
89Cheung, CY, Brace, RA. Fetal hypoxia elevates plasma atrial natriuretic factor concentration. Am J Obstet Gynecol 1988; 159: 1263–68.CrossRefGoogle ScholarPubMed
90Smith, FG, Sato, T, Varilee, VA, Robillard, JE. Atrial natriuretic factor during fetal and postnatal life; a review. J Dev Physiol 1989; 12: 55–62.Google ScholarPubMed
91Tomobe, Y, Miyauchi, T, Saito, A, Yanagisawa, M, Kimura, K, Goto, K et al. Effects of endothelin on the renal artery from spontaneously hypertensive and Wistar Kyoto rats. Eur J Pharmacol 1988; 152: 373–74.CrossRefGoogle ScholarPubMed
92Uchida, Y, Ninomiya, H, Saotome, M, Nomura, A, Ohtsuka, M, Yanagisawa, M et al. Endothelin, a novel vasoconstrictor peptide, a potent bronchoconstrictor. Eur J Pharmacol 1988; 154: 227–28.CrossRefGoogle Scholar
93Yanagisawa, M, Kurihawa, H, Kimura, S, Tomobe, Y, Kobaysashi, Y, Mitsui, Y et al. A novel potent vasoconstrictor peptide produced by vascular endothelial cells. Nature 1988; 332: 411–15.CrossRefGoogle ScholarPubMed
94Cassin, S, Kristova, V, Davis, T, Kadowitz, P, Gause, G. Tone-dependent responses to endothelin in the isolated perfused fetal sheep pulmonary circulation in situ. J Appl Physiol 1991; 70: 1228–34.CrossRefGoogle ScholarPubMed
95Chatfield, BA, McMurtry, IF, Stacia, LH, Abman, SH. Hemodynamic effects of endothelin-I on ovine fetal pulmonary circulation. Am J Physiol 1991; 261: R182–R187.Google Scholar
96Furchgott, RF, Zawadski, JV. The obligatory role of endothelial cells in the relaxation of the arterial smooth muscle by acetylcholine. Nature 1980; 288: 373–76.CrossRefGoogle ScholarPubMed
97Leffler, CW, Hessler, JR, Green, RS. The onset of breathing at birth stimulates pulmonary vascular prostacyclin synthesis. Ped Res 1984; 18: 938–42.CrossRefGoogle ScholarPubMed
98Yanagisawa, M, Masaki, T. Endothelin, a novel endothelium derived peptide. Pharmacological activities, regulation and possible role in cardiovascular control. Biochem Pharmacol 1989; 38: 1877–83.Google Scholar
99Marriott, JF, Marshall, JM. Effects of hypoxia upon contractions evoked in isolated rabbit pulmonary artery by potassium and noradrenaline. J Physiol 1990; 422: 15–28.CrossRefGoogle ScholarPubMed
100Tenney, SM. Hypoxic vasorelaxation. NIPS 1990; 5: 40.Google Scholar
101Walker, BR, Brizzee, BL. Cardiovascular responses to hypoxia and hypercapnia in barodenervated rats. J Appl Physiol 1990; 68: 678–86.CrossRefGoogle ScholarPubMed
102Lüscher, TF, Dohi, Y. Endothelium-derived relaxing factor and endothelin in hypertension. NIPS 1992; 7: 120–23.Google Scholar
103Lüscher, TF, Vanhoutte, PM. The endothelium: modulator of cardiovascular function. Boca Raton, FL, 1990: 1–215.Google Scholar
104Dohi, Y, Thiel, MA, Bühler, FR, Lüscher, TF. Activation of endothelial L-arginine pathway by pressurized mesenteric resistance arteries: effect of age and hypertension. Hypertension 1990; 16: 170–79.CrossRefGoogle Scholar
105Vallance, P, Collier, J, Moncada, S. Effects of endothelium-derived nitric oxide on peripheral arteriolar tone in man. Lancet 1989; 1: 997–1000.CrossRefGoogle Scholar
106Linder, L, Kiowski, W, Bühler, FR, Lüscher, TF. Indirect evidence for the release of endothelium-derived relaxing factor in human forearm circulation in vivo: blunted responses in essential hypertension. Circulation 1990; 81: 1762–67.CrossRefGoogle ScholarPubMed
107Edwards, AD, Takei, Y, Peebles, DM, Lorek, A, Cope, M, Delpy, DT et al. In vivo quantitation of effects of L-NAME on the cerebral circulation of newborn piglets by near infrared spectroscopy. Proc Physiol Soc 1992: Oxford meeting C71.Google Scholar
108Burton, RG, Gorewit, RC. ‘Ultrasonic Flowmeter’ – uses transit-time techniques. Med Electronics 1984; 15: 68–73.Google Scholar
109Giussani, DA, Spencer, JAD, Moore, PJ, Bennet, L, Hanson, MA. Afferent and efferent components of the cardiovascular reflex responses to acute hypoxia in term fetal sheep. J Physiol 1993; 461: 431–49.CrossRefGoogle ScholarPubMed
110Martin, CB. Pharmacological aspects of fetal heart rate regulation during hypoxia. In: Kunzel, Wed, Fetal heart rate monitoring. Berlin: Springer-Verlag, 1985: 170–84.CrossRefGoogle Scholar
111Hohimer, AR, Bissonnette, JM, Richardson, BS, Machida, CM. Central chemical regulation of breathing movements in fetal lambs. Respir Physiol 1983; 52: 99–111.CrossRefGoogle ScholarPubMed
112Koos, BJ. Central stimulation of breathing movements in fetal lambs by prostaglandin synthetase inhibitors. J Physiol 1985; 362: 455–66.CrossRefGoogle ScholarPubMed
113Mitchell, RA, Loeschcke, HH, Massion, WH, Severinghans, JW. Respiratory responses mediated through superficial chemosensitive areas on the medulla. J Appl Physiol 1963; 18: 523–33.CrossRefGoogle ScholarPubMed
114Coates, EL, Aihua, L, Nattie, EE. Widespread sites of brain stem ventilatory chemoreceptors. J Appl Physiol 1993; 75: 5–14.CrossRefGoogle ScholarPubMed
115Severinghaus, JW. Widespread sites of brain stem ventilatory chemoreceptors. J Appl Physiol 1993; 75: 3.CrossRefGoogle ScholarPubMed
116Fidone, SJ, Gonzalez, C. Initiation and control of chemoreceptor activity in the carotid body. In: Fishman, AP ed, Handbook of physiology, section 3; the respiratory system. Volume 2 part 1. Maryland: American Physiological Society, 1986: 247–312.Google Scholar
117Cross, KW, Malcolm, JL. Evidence of carotid body and sinus activity in new-born and foetal animals. J Physiol 1952; 118: 10P–11P.Google Scholar
118Cross, KW. Respiration in the new-born baby. Br Med Bull 1961; 17: 160–63.CrossRefGoogle ScholarPubMed
119Harned, HS, Mackinney, LG, Berryhill, WS, Holmes, CK. Effects of hypoxia and acidity on the initiation of breathing in the fetal lamb at term. Am J Disabled Child 1966; 112: 334–42.Google ScholarPubMed
120Biscoe, TJ, Purves, MJ, Sampson, SR. Types of nervous activity which may be recorded from the carotid sinus nerve in the sheep foetus. J Physiol 1969; 202: 1–23.CrossRefGoogle ScholarPubMed
121Biscoe, TJ, Purves, MJ. Carotid body chemoreceptor activity in the new-born lamb. J Physiol 1967; 190: 443–54.CrossRefGoogle ScholarPubMed
122Blanco, CE, Dawes, GS, Hanson, MA, McCooke, HB. The response to hypoxia of arterial chemoreceptors in fetal sheep and new-born lambs. J Physiol 1984; 351: 25–37.CrossRefGoogle ScholarPubMed
123Blanco, CE, Dawes, GS, Hanson, MA, McCooke, HB. Carotid baroreceptors in fetal and newborn sheep. Pediatr Res 1988; 24: 342–46.CrossRefGoogle ScholarPubMed
124Dawes, GS, Duncan, SLB, Lewis, BV, Merlet, CL, Owen-Thomas, JB, Reeves, JT. Cyanide stimulation of the systemic arterial chemoreceptors in foetal lambs. J physiol 1969; 201: 117–28.CrossRefGoogle ScholarPubMed
125Dawes, GS, Duncan, SLB, Lewis, BV, Merlet, CL, Owen-Thomas, JB, Reeves, JT. Hypoxaemia and aortic chemoreceptor function in foetal lambs. J Physiol 1969; 201: 105–16.CrossRefGoogle ScholarPubMed
126Ismay, MJA, Lumbers, ER, Stevens, AD. The action of angiotensin 2 on the baroreflex response of the conscious ewe and the conscious fetus. J Physiol 1979; 288: 467–79.CrossRefGoogle ScholarPubMed
127Dawes, GS, Johnston, BM, Walker, DW. Relationship of arterial pressure and heart rate in fetal, newborn and adult sheep. J Physiol 1980; 309: 405–17.CrossRefGoogle ScholarPubMed
128Shinebourne, EA, Vapaavuori, EK, Williams, RL, Heymann, MA, Rudolph, AM. Development of baroreflex activity in unanaesthetized fetal and neonatal sheep. Circ Res 1972; 31: 710–18.CrossRefGoogle Scholar
129Maloney, JE, Cannata, J, Dowling, MH, Else, W, Ritchie, B. Baroreflex activity in conscious fetal and newborn lambs. Biol Neonate 1977; 31: 340–50.CrossRefGoogle ScholarPubMed
130Itskovitz, J, Rudolph, AM. Denervation of arterial chemoreceptors and baroreceptors in fetal lambs in utero. Am J Physiol 1982; 242: H916–H920.Google ScholarPubMed
131Dawes, GS, Comroe, JH. Chemoreflexes from the heart and lungs. Physiol Rev 1954; 34: 167–201.CrossRefGoogle ScholarPubMed
132Kumar, P, Hanson, MA. Post-natal resetting of the hypoxic sensitivity of aortic chemoreceptors in the lamb. In: Eyzaguirre, C, Fidone, SJ, Fitzgerald, RS, Lahiri, S, McDonald, DM eds, Arterial chemoreceptors.Berlin: Springer-Verlag, 1990: 279–84.CrossRefGoogle Scholar
133Itskovitz, J, LaGamma, EF, Bristow, J, Rudolph, AM. Cardiovascular responses to hypoxaemia in sino-aortic denervated fetal sheep. Ped Res 1991; 30: 381–85.CrossRefGoogle Scholar
134Walker, AM, Cannata, JP, Dowling, MH, Ritchie, B, Maloney, JE. Age-dependent pattern of autonomic heart rate control during hypoxia in fetal and newborn lambs. Biol Neonate 1979; 35: 198–208.CrossRefGoogle ScholarPubMed
135Parer, JT, Krueger, TR, Harris, JL. Fetal oxygen consumption and mechanisms of heart rate response during artificially produced late decelerations of fetal heart rate in sheep. Am J Obstet Gynecol 1980; 136: 478–82.CrossRefGoogle ScholarPubMed
136Blanco, CE, Dawes, GS, Walker, DW. Effect of hypoxia on polysynaptic hind-limb reflexes of unanaesthetized fetal and new-born lambs. J Physiol 1983; 339: 453–66.CrossRefGoogle ScholarPubMed
137Lewis, AB, Donovan, M, Platzker, ACG. Cardiovascular responses to autonomic blockade in hypoxemic fetal lambs. Biol Neonate 1980; 37: 233–42.CrossRefGoogle ScholarPubMed
138Bartelds, B, van Bel, F, Teitel, D, Rudolph, AM. Carotid, not aortic, chemoreceptors mediate the fetal cardiovascular response to acute hypoxemia in lambs. Ped Res 1993; 34: 51–55.CrossRefGoogle Scholar
139Watanabe, T, Bennet, L, Green, L, Hanson, MA. Changes in fetal heart rate variability in acute hypoxaemia in fetal sheep. Soc for the Study of Fetal Physiol 20th annual meeting, Plymouth, 1993: A4.Google Scholar
140Clarke, JA, Daly, MB. The volume of the carotid body and periadventitial type 1 and 2 cells in the carotid bifurcation region of the fetal cat and kitten. Anat Embryol 1985; 173: 117–27.CrossRefGoogle Scholar
141Kollmeyer, KR, Kleinman, LI. A respiratory venous chemoreceptor in the young dog. J Appl Physiol 1975; 38: 819–26.CrossRefGoogle Scholar
142Lauweryns, JM, De Bock, P, Guelinckx, P, Decramer, M. Effects of unilateral hypoxia on neuroepithelial bodies in rabbit lungs. J Appl Physiol 1983; 55: 1665–68.CrossRefGoogle ScholarPubMed
143Lauweryns, JM, Van Lommel, AT, Dom, RJ. Innervation of rabbit intrapulmonary neuroepithelial bodies. J Neurol Sci 1985; 67: 81–92.CrossRefGoogle ScholarPubMed
144Howe, A, Pack, RJ, Wise, JCM. Arterial chemoreceptor-like activity in the abdominal vagus of the rat. J Physiol 1981; 320: 309–18.CrossRefGoogle ScholarPubMed
145Ledsome, JR, Kan, WO. Reflex changes in hind limb and renal vascular resistance in response to distension of the isolated pulmonary arteries of the dog. Circ Res 1977; 40: 64–72.CrossRefGoogle Scholar
146Spyer, KM. The central nervous regulation of reflex circulatory control. In: Loewy, AD, Spyer, KM eds, Central regulation of autonomic functions. New York: Oxford University Press, 1990: 168–88.CrossRefGoogle Scholar
147Spyer, KM. Neural organisation and control of the baroreceptor reflex. Rev Physiol, Biochem, Pharmacol 1981; 88: 23–124.CrossRefGoogle ScholarPubMed
148Jordan, D, Spyer, KM. Brainstem integration of cardiovascular and pulmonary afferent activity. Prog Brain Res 1986; 67: 295–314.CrossRefGoogle ScholarPubMed
149Paton, JFR, Spyer, KM. Cerebellar cortical regulation of circulation. NIPS 1992; 7: 124–29.Google Scholar
150Dawes, GS, Gardner, WN, Johnston, BM, Walker, DW. Breathing in fetal lambs: the effect of brain stem section. J Physiol 1983; 335: 535–53.CrossRefGoogle ScholarPubMed
151Gluckman, PD, Johnston, BM. Lesions in the upper lateral pons abolishes the hypoxic depression of fetal breathing in unanaesthetized fetal lambs in utero. J Physiol 1987; 382: 373–83.CrossRefGoogle ScholarPubMed
152Gluckman, PD, Johnston, BM. Peripheral chemoreceptors respond to hypoxia in pontine-lesioned fetal lambs in utero. J Appl Physiol 1993; (in press).Google Scholar
153Moore, PJ, Parkes, MJ, Noble, R, Hanson, MA. Reversible blockade of the secondary fall of ventilation during hypoxia in anaesthetized newborn sheep by focal cooling in the brain stem. J Physiol 1991; 438: 242P.Google Scholar
154Ackland, GL, Moore, PJ, Bohm, MCB, Hanson, MA. Contrasting effects of hypoxia on brainstem mechanisms mediating phrenic responses to chemoreceptor and to somatic afferent inputs. Eur Soc for the Study and Prevention of Infant Deaths. III Congress, Oxford, 1993: 26.Google Scholar
155Dawes, GS. Fetal and neonatal physiology. Chicago: Yearbook Medical Publishers, 1968.Google Scholar
156Pappano, AJ. Ontogenic development of autonomic neuroeffector transmission and transmitter reactivity in embryonic and fetal hearts. Pharmacol Rev 1977; 29: 3–33.Google Scholar
157Berman, W, Goodlin, RC, Heymann, MA, Rudolph, AM. Relationship between pressure and flow in the uterine circulation of the sheep. Circ Res 1976; 38: 262–66.CrossRefGoogle ScholarPubMed
158Cohn, HE, Piasecki, GJ, Jackson, BT. The role of autonomic nervous control in the fetal cardiovascular response to hypoxemia. In: Longo, LD, Reneau, DD eds, Fetal and newborn cardiovascular physiology. Vol 2. New York: Garland, 1978: 249.Google Scholar
159Ikenoue, T, Martin, CB, Murata, Y, Ettinger, BB, Lu, PS. Effect of acute hypoxemia and respiratory acidosis on the fetal heart rate in monkeys. Am J Obstet Gynecol 1981; 141: 797.CrossRefGoogle ScholarPubMed
160Parer, JT. Effect of atropine on heart rate and oxygen consumption of the hypoxic fetus. Gynecol Invest 1979; 8: 50.Google Scholar
161Caldeyro-Barcia, R, Mendez-Bauer, C, Poseiro, JJ, Escarcena, LA, Pose, SV, Bieniarz, J et al. Control of human fetal heart rate during labour. In: Cassels, DE ed, The heart and circulation in the newborn and infant. New York and London: Grune and Stratton, 1966: 7–36.Google Scholar
162Colebatch, HJH, Dawes, GS, Goodwin, JW, Nadeau, RA. The nervous control of the circulation in the fetal and newly expanded lungs of the lamb. J Physiol 1965; 178: 544–62.CrossRefGoogle ScholarPubMed
163Assali, NS, Brinkman, CR, Woods, R, Dandavirw, A, Nuwayhid, B. Ontogenesis of the autonomic control of cardiovascular function in sheep. In: Longo, LD, Reneau, DD eds, Fetal and newborn cardiovascular physiology. Vol 1. New York: Garland STPM Press, 1978: 47–92.Google Scholar
164Tabsch, K, Nuwayhid, B, Murad, S, Ushioda, E, Erkkola, R, Brinkman, CR et al. Circulatory effects of chemical sympathectomy in fetal and adult sheep. Am J Physiol 1982; 243: H113–H122.Google Scholar
165Iwamoto, HS, Rudolph, AM, Mirkin, BL, Keil, LC. Circulatory and humoral responses of sympathectomized fetal sheep to hypoxemia. Am J Physiol 1983; 245: H767–H772.Google ScholarPubMed
166Schuijers, JA, Walker, DW, Browne, CA, Thorburn, GD. Effect of hypoxemia on plasma catecholamines in intact and immunosympathectomized fetal lambs. Am J Physiol 1986; 251: R893–R900.Google ScholarPubMed
167Court, DJ, Parer, JT, Block, BS, Llanos, AJ. The effects of β adrenergic blockade on blood flow distribution during hypoxemia in fetal sheep. J Dev Physiol 1984; 6: 349–58.Google ScholarPubMed
168Evers, JLH, De Hann, J, Jongsma, HW, Crevels, J, Arts, THM, Martin, CB. The pre-ejection period of the fetal cardiac cycle. 1. Umbilical cord occlusions. 2. Maternal common internal iliac artery occlusions. Eur J Obstet Gynecol Reprod Biol 1981; 11: 401–419.CrossRefGoogle Scholar
169Jensen, A, Hanson, MA. Circulatory responses to acute asphyxia in intact and chemodenervated fetal sheep near term. J Dev Physiol 1993; (in press).Google Scholar
170Brace, RA, Cheung, CY. Role of catecholamines in mediating fetal blood volume decrease during acute hypoxia. Am J Physiol 1987; 243: R520–R525.Google Scholar
171Harper, MA, Rose, JC. Arginine vasopressin infusion stimulates adrenocorticotropic hormone and cortisol release in the ovine fetus. Am J Obstet Gynecol 1988; 159: 983–88.CrossRefGoogle ScholarPubMed
172Hanley, DF, Wilson, DA, Feldman, MA, Traystman, RJ. Peripheral chemoreceptor control of neurohypophysial blood flow. Am J Physiol 1988; 254: H742–H750.Google ScholarPubMed
173Raff, H, Shinsako, J, Keil, LC, Dallmann, MF. Vasopressin, ACTH and corticosteroids during hypercapnia and graded hypoxia in dogs. Am J Physiol 1983; 244: E453–E458.Google ScholarPubMed
174Share, L, Levy, MN. Effect of carotid chemoreceptor stimulation on plasma antidiuretic harmone titer. Am J Physiol 1966; 210: 157–61.CrossRefGoogle Scholar
175Giussani, DA, McGarrigle, HHC, Spencer, JAD, Moore, PJ, Bennet, L, Hanson, MA. Carotid sinus nerve section does not affect plasma vasopressin levels during acute isocapnic hypoxia in term fetal sheep. J Physiol 1993; (submitted).Google Scholar
176Giussani, DA, McGarrigle, HHC, Bennet, L, Moore, PJ, Spencer, JAD, Hanson, MA. Carotid sinus nerve section delays the increase in plasma cortisol during acute hypoxia in chronically-prepared fetal sheep. J Physiol 1993; (submitted).Google Scholar
177Myers, DA, Robertshaw, D, Nathanielsz, PW. Effect of bilateral splanchnic nerve section on adrenal function in the ovine fetus. Endocrinology 1990; 127: 2328–35.CrossRefGoogle ScholarPubMed
178Edwards, AV, Jones, CT. The effect of splanchnic nerve stimulation on adrenocortical activity in conscious calves. J Physiol 1987; 382: 385–96.CrossRefGoogle ScholarPubMed
179Dijxhoorn, MJ, Visser, GHA, Touwen, BCL, Huisjes, HJ. Apgar score meconium and acidaemia at birth in small-for-gestational-age infants born at term, and their relation to neurological morbidity. Br J Obstet Gynaecol 1987; 94: 873–79.CrossRefGoogle ScholarPubMed
180Hull, J, Dodd, K. What is birth asphyxia?. Br J Obstet Gynaecol 1991; 98: 953–55.CrossRefGoogle ScholarPubMed
181Hill, A. Current concepts of hypoxic-ischaemic cerebral injury in the newborn. Ped Neurol 1991; 7: 317–25.CrossRefGoogle Scholar
182Creasy, RK, de Swiet, M, Kahanpaa, KV, Young, WP, Rudolph, AM. Pathophysiological changes in the foetal lambs with growth retardation. In: Comline, RS, Cross, KW, Dawes, GS, Nathanielsz, PW eds, Foetal and neonatal physiology. Cambridge: Cambridge University Press, 1973: 398–402.Google Scholar
183Alexander, G. Studies on the placenta of the sheep (Ovis aries L): effect of surgical reduction in the number of caruncles. J Reprod Fertil 1964; 7: 307–22.CrossRefGoogle ScholarPubMed
184Robinson, JS, Kingston, EJ, Jones, CT, Thorburn, GD. The effect of removal of endometrial caruncles on fetal size and metabolism. J Dev Physiol 1979; 1: 379–98.Google ScholarPubMed
185Edelstone, DI, Paulone, ME, Maljovec, JJ, Hagberg, M. Effects of maternal anaemia on cardiac output, systemic oxygen consumption and regional blood flow in pregnant sheep. Am J Obstet Gynecol 1987; 156: 740–48.CrossRefGoogle ScholarPubMed
186Jacobs, R, Robinson, JS, Owens, JA, Falconer, J, Webster, MED. The effect of prolonged hypobaric hypoxia on growth in fetal sheep. J Dev Physiol 1988; 10: 97–112.Google ScholarPubMed
187Kitanaka, T, Alonso, JG, Gilbert, RD, Benjamin, LS, Clemons, GK, Longo, LD. Fetal responses to long-term hypoxemia in sheep. Am J Physiol 1989; 256: R1348–R1354.Google ScholarPubMed
188Clark, K, Durnwald, M, Austin, J. A model for studying chronic reduction in uterine blood flow in pregnant sheep. Am J Physiol 1982; 242: H297–H301.Google Scholar
189Bocking, AD, Harding, R, Wickham, PJD. Effects of reduced uterine blood flow on accelerations and decelerations in heart rate of fetal sheep. Am J Obstet Gynecol 1986; 154: 329–35.CrossRefGoogle ScholarPubMed
190Bocking, AD, Gagnon, R, White, SE, Homan, J, Milne, KM, Richardson, BS. Circulatory responses to prolonged hypoxemia in fetal sheep. Am J Obstet Gynecol 1988; 159: 1418–24.CrossRefGoogle ScholarPubMed
191Bocking, AD, White, S, Gagnon, R, Hansford, H. Effect of prolonged hypoxemia on fetal heart rate accelerations and decelarations in sheep. Am J Obstet Gynecol 1989; 161: 722–27.CrossRefGoogle Scholar
192Challis, JRG, Fraher, L, Oosterhuis, J, White, SE, Bocking, AD. Fetal and maternal endocrine responses to prolonged reductions in uterine blood flow in pregnant sheep. Am J Obstet Gynecol 1989; 160: 926–32.CrossRefGoogle ScholarPubMed
193Hooper, SB, Coulter, CL, Deayton, JM, Harding, R, Thorburn, GD. Fetal endocrine responses to prolonged hypoxemia in sheep. Am J Physiol 1990; 259: R703–708.Google ScholarPubMed
194Hooper, SB, Bocking, AD, White, SE, Challis, JRG, Han, VKM. DNA synthesis is reduced in selected fetal tissues during prolonged hypoxemia. Am J Physiol 1991; 261: R508–R514.Google ScholarPubMed
195Bennet, L, Watanabe, T, Spencer, JAD, Hanson, MAH. The effects of chronic hypoxemia in late gestation fetal sheep. Int Union of Physiological Sciences. 32nd Congress, Glasgow, 1993: Abstract 214.14/P.Google Scholar
196Koos, BJ, Kitanaka, T, Matsuda, K, Gilbert, RD, Longo, LD. Fetal breathing adaptation to prolonged hypoxaemia in sheep. J Dev Physiol 1988; 10: 161–66.Google ScholarPubMed
197Meschia, G, Prystowsky, H, Hellegers, A, Huckabee, W, Metcalfe, J, Barron, D. Observations on the oxygen supply to the fetal llama. Q J Exp Physiol 1960; 45: 284–91.CrossRefGoogle Scholar
198Giussani, DA, Riquelme, RA, Gaete, CR, Moraga, FA, Sanhueza, EM, Hanson, MA et al. Rapid intense peripheral vasoconstriction in the llama fetus in utero during acute hypoxaemia at 0.6–0.7 of gestation. Proc Physiol Soc, University College, London, 1993: Abstract 66P.Google Scholar
199Giussani, DA, McGarrigle, HHC, Riquelme, RA, Moraga, FA, Gaete, CR, Sanhueza, EM et al. Endocrine responses of llama fetus in utero during acute hypoxaemia at 0.6–0.7 of gestation. Proc Physiol Soc, Southampton, 1993: Abstract 64P.Google Scholar