Generation and Transmission of Endothelium-Dependent Vasodilator Signals
The crucial role of the endothelium in the local control of vascular tone by the release of vasoactive autacoids has only become apparent during the last decade. The most important of these autacoids, released under basal and stimulated conditions appear to be prostacyclin (PGI2) (Moncada, 1985) and the very unstable endothelium-derived relaxant factor (EDRF) (Furchgott, 1983). The latter was recently identified as nitric oxide (Palmer et al., 1987). A large number of endogenous vasoactive substances (e.g. acetylcholine, ATP, bradykinin, histamine and substance P) as well as biophysical conditions (low oxygen tension, viscous drag on the luminal surface of the endothelial cells, pulsatile stretching of the vascular wall) have been found to stimulate the release of both autacoids (Bassenge and Busse, 1988; Furchgott, 1983). The mechanisms of vasodilation elicited by both autacoids are different. While the smooth muscle relaxation induced by PGI2 is correlated with an increase in cellular cyclic AMP, that induced by EDRF is associated with a rise in cyclic GMP.
KeywordsSoluble Guanylate Cyclase Intracellular Free Calcium Femoral Blood Flow Washed Human Platelet Reduce Oxygen Uptake
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