Book contents
- Frontmatter
- Contents
- List of contributors
- Editors' preface
- PART I PHYSIOLOGY
- 1 History of platelets
- 2 Production of platelets
- 3 Morphology and ultrastructure of platelets
- 4 Platelet heterogeneity: physiology and pathological consequences
- 5 Platelet membrane proteins as adhesion receptors
- 6 Dynamics of the platelet cytoskeleton
- 7 Platelet organelles
- 8 Platelet receptors for thrombin
- 9 Platelet receptors: ADP
- 10 Platelet receptors: prostanoids
- 11 Platelet receptors: collagen
- 12 Platelet receptors: von Willebrand factor
- 13 Platelet receptors: fibrinogen
- 14 Platelet signalling: GTP-binding proteins
- 15 Platelet phospholipases A2
- 16 Roles of phospholipase C and phospholipase D in receptor-mediated platelet activation
- 17 Platelet signalling: calcium
- 18 Platelet signalling: protein kinase C
- 19 Platelet signalling: tyrosine kinases
- 20 Platelet signalling: cAMP and cGMP
- 21 Platelet adhesion
- 22 The platelet shape change
- 23 Aggregation
- 24 Amplification loops: release reaction
- 25 Amplification loops: thromboxane generation
- 26 Platelet procoagulant activities: the amplification loops between platelets and the plasmatic clotting system
- 27 Platelets and chemotaxis
- 28 Platelet–leukocyte interactions relevant to vascular damage and thrombosis
- 29 Vascular control of platelet function
- PART II METHODOLOGY
- PART III PATHOLOGY
- PART IV PHARMOLOGY
- PART V THERAPY
- Afterword: Platelets: a personal story
- Index
- Plate section
23 - Aggregation
from PART I - PHYSIOLOGY
Published online by Cambridge University Press: 10 May 2010
- Frontmatter
- Contents
- List of contributors
- Editors' preface
- PART I PHYSIOLOGY
- 1 History of platelets
- 2 Production of platelets
- 3 Morphology and ultrastructure of platelets
- 4 Platelet heterogeneity: physiology and pathological consequences
- 5 Platelet membrane proteins as adhesion receptors
- 6 Dynamics of the platelet cytoskeleton
- 7 Platelet organelles
- 8 Platelet receptors for thrombin
- 9 Platelet receptors: ADP
- 10 Platelet receptors: prostanoids
- 11 Platelet receptors: collagen
- 12 Platelet receptors: von Willebrand factor
- 13 Platelet receptors: fibrinogen
- 14 Platelet signalling: GTP-binding proteins
- 15 Platelet phospholipases A2
- 16 Roles of phospholipase C and phospholipase D in receptor-mediated platelet activation
- 17 Platelet signalling: calcium
- 18 Platelet signalling: protein kinase C
- 19 Platelet signalling: tyrosine kinases
- 20 Platelet signalling: cAMP and cGMP
- 21 Platelet adhesion
- 22 The platelet shape change
- 23 Aggregation
- 24 Amplification loops: release reaction
- 25 Amplification loops: thromboxane generation
- 26 Platelet procoagulant activities: the amplification loops between platelets and the plasmatic clotting system
- 27 Platelets and chemotaxis
- 28 Platelet–leukocyte interactions relevant to vascular damage and thrombosis
- 29 Vascular control of platelet function
- PART II METHODOLOGY
- PART III PATHOLOGY
- PART IV PHARMOLOGY
- PART V THERAPY
- Afterword: Platelets: a personal story
- Index
- Plate section
Summary
Introduction
Platelet aggregation is involved in the formation of hemostatic plugs and arterial thrombi. Under normal circumstances, platelets are non-adhesive and circulate singly, but following vessel wall injury they adhere to the injury site and to each other. During the hemostatic process, platelet aggregates, stabilized by fibrin, arrest bleeding from injured or severed vessels. In contrast to this useful function, platelet aggregates that form on injured vessels, on ruptured atherosclerotic plaques, or in regions of high shear contribute to the narrowing of blood vessels. If thrombi are unstable, they may embolize and block smaller vessels downstream from an injury site. Since platelet aggregation has a major role in the clinical complications of atherosclerosis (myocardial infarction, ischemic stroke, and peripheral vascular disease), there is intensive study of the processes involved in platelet aggregation and of inhibitors of platelet activation.
In vivo, activators of platelets include the agonists that are listed in Table 23.1. Receptors for some of the most important agonists are discussed in Chapters 8–11. Aggregating agents can act singly, and are frequently studied singly in vitro, but in vivo they undoubtedly act in concert with each other in a process described as synergism. Synergistic responses result in a combined effect that is greater than the additive effects of the single stimuli. In vivo, the most important aggregating agents are collagen in the vessel wall, ADP from red blood cells or released from the platelets themselves, thromboxane A2 formed by stimulated platelets, and thrombin, although other agonists such as serotonin may contribute to the aggregation process.
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- Information
- Platelets in Thrombotic and Non-Thrombotic DisordersPathophysiology, Pharmacology and Therapeutics, pp. 338 - 356Publisher: Cambridge University PressPrint publication year: 2002
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