Endothelial regulation of vascular tone, inflammation and thrombosis
THE CONTEXT
The endothelium maintains vascular homeostasis by balancing vasoactive mediators and regulating inflammatory cell recruitment and thrombus turnover.
Vascular tone
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Endothelial vasodilators include nitric oxide, prostacyclin and endothelium-derived hyperpolarising factor; vasoconstrictors include angiotensin II and endothelin-1.
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The balance between these mediators regulates vascular tone and blood pressure. Endothelial damage can disrupt this balance, producing vascular dysfunction, tissue ischaemia and hypertension.
Inflammatory cell recruitment
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Activated endothelium expresses E-selectin, intercellular adhesion molecule type 1 (ICAM-1) and platelet–endothelial cell adhesion molecule type 1 (PECAM-1).
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These surface receptors mediate rolling, adhesion and migration of inflammatory leucocytes into the subintima.
Thrombus formation and dissolution
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The endothelium stores and releases von Willebrand factor, a multimeric glycoprotein that promotes platelet adhesion to denuded surfaces, especially in the arterial vasculature.
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Once intravascular thrombus forms, tissue plasminogen activator is rapidly released from endothelial stores to induce fibrinolysis and thrombus dissolution.
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These processes contribute to atherosclerosis development and progression. Endothelial dysfunction and injury are central to the pathogenesis of many cardiovascular disease states.