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Endothelial cells can initiate contraction(constriction)of the vascular smooth muscle cells that surround them.Such endothelium-dependent,acute increases in contractile tone can be due to the withdrawal of the production of nitric oxide,to the production of vasoconstrictor peptides(angiotensin II,endothelin-1),to the formation of oxygen-derived free radicals(superoxide anions)and/or the release of vasoconstrictor metabolites of arachidonic acid.The latter have been termed endothelium-derived contracting factor(EDCF)as they can contribute to moment-to-moment changes in contractile activity of the underlying vascular smooth muscle cells.To judge from animal experiments,EDCF-mediated responses are exacerbated when the production of nitric oxide is impaired as well as by aging,spontaneous hypertension and diabetes.To judge from human studies,they contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive patients.Since EDCF causes vasoconstriction by activation of the TP-receptors on the vascular smooth muscle cells,selective antagonists at these receptors prevent endothelium-dependent contractions,and curtail the endothelial dysfunction in hypertension and diabetes.
Endothelial cells constricting of the vascular smooth muscle cells that surround them. Such endothelium-dependent, acute increases in contractile tone can be due to the withdrawal of the production of nitric oxide, to the production of vasoconstrictor peptides (angiotensin II , endothelin-1), to the formation of oxygen-derived free radicals (superoxide anions) and / or the release of vasoconstrictor metabolites of arachidonic acid. The latter have been termed endothelium-derived contracting factor (EDCF) as they can contribute to moment -to-moment changes in contractile activity of the underlying vascular smooth muscle cells. To judge from animal experiments, EDCF-mediated responses are exacerbated when the production of nitric oxide is impaired as well as by aging, spontaneous hypertension and diabetes. To judge from human studies, they contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive patients. Since EDCF causes vasoco nstriction by activation of the TP-receptors on the vascular smooth muscle cells, selective antagonists at these receptors prevent endothelium-dependent contractions, and curtail the endothelial dysfunction in hypertension and diabetes.