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
4 - Platelet heterogeneity: physiology and pathological consequences
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
Individual platelets vary in terms of volume, density and reactivity. Ever since the seminal paper by Karpatkin, the biological significance of this platelet heterogeneity has been strongly contested.
Platelet volume, usually measured as mean platelet volume (MPV), has been the most frequently studied platelet physical variable. During steady-state hematopoeisis the platelet volume distribution approaches log normality with platelets ranging in size from <2 µm3 to >15 µm3 in volume. This variation in size is considerably greater than that observed for other circulating blood elements in any mammal. This heterogeneity forms the basis of the controversy with respect to the physiological relevance of platelet volume and reactivity.
Separation of platelets into size dependent subpopulations has shown that the granular contents of these cells is directly proportional to their volume. Importantly, the ability of platelets to affect each other and their environment as measured by aggregation and total amount of granular contents released, is proportional to their size and confirmed by the finding that platelet volume correlates with absolute platelet function. The physiological explanation for this lies in the observation that high-density platelets contain significantly higher concentrations of alpha granule proteins (β thromboglobulin, von Willebrand factor), dense granule markers (5-HT, calcium), mitochondrial marker enzymes (monamine oxidase, cytochrome oxidase, glutamate dehydrogenase and NADP-dependent isocitrate dehydrogenase), glycogen and express more of the GPIIb/IIIa receptor.
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- Information
- Platelets in Thrombotic and Non-Thrombotic DisordersPathophysiology, Pharmacology and Therapeutics, pp. 70 - 79Publisher: Cambridge University PressPrint publication year: 2002