The effects of propofol and thiopental on three vasoconstrictors, acetylcholine, histamine, and serotonin were studied in isolated porcine and human coronary artery rings. Propofol and thiopental attenuated the contractile response to all mediators in a dose-dependent manner. This dilating effect was fairly weak using low concentrations (propofol 1 μg mL−1 and 10 μg mL−1, thiopental 5 μg mL−1 and 10 μg mL−1). In the presence of high concentrations (propofol 100 μg mL−1, thiopental 50 μg mL−1) marked relaxation was observed (propofol −32% up to −49%, P < 0,05; thiopental −23% up to −67%, P < 0.05). These dilating effects were seen both in intact and denuded rings, the differences were not significant. Human coronary artery segments were relaxed by thiopental (−22% to −76%) and propofol (−11% to −67%) to a similar extent. Our data indicate that propofol and thiopental relax isolated coronary segments in a dose-dependent manner, and that there is no evidence that these effects are dependent of endothelial factors.

The aim of this study was to elucidate the influence of four neuromuscular blocking substances on coronary vascular tone using the model of isolated porcine coronary artery segments. We studied the effects of four muscle relaxants, atracurium, pancuronium, rocuronium, and vecuronium (0.1, 1, and 10 μg mL−1 each), on the contractile response to three vasoconstrictors: acetylcholine, histamine, and serotonin. None of the neuromuscular blocking agents under investigation exerted a significant influence on the vasoconstricting effects of these mediators except for pancuronium, which dose-dependently attenuated acetylcholine-mediated contractions (−10.8% attenuation for 10 μg mL−1 pancuronium, P < 0.05). There was no difference between vessels with intact endothelium and denuded preparations. It is concluded that high-dose pancuronium exerts an antimuscarinic effect in vascular smooth muscle. The other neuromuscular agents studied do not alter vascular reactivity of isolated porcine coronary arteries.