Agonist Stimulated Changes in Human Endothelial Cell Cytosolic Calcium
A considerable amount of evidence exists to suggest that a rise in cytoplasmic free calcium concentration, [Ca2+]i, evokes morphological, metabolic and secretory responses in endothelial cells in response to stimulation by many inflammatory mediators. One of the most potent agents for stimulating the release of the vasodilators endothelial-derived relaxing factor (EDRF) and prostacyclin (PGI2) is the calcium ionophore A23187. However, the hypothesis that elevated [Ca2+]i is the physiological messenger is held with some caution since A23187-evoked rises in [Ca2+]i sufficient to evoke these responses can conceivably be far larger than those physiologically attained on stimulation with inflammatory mediators. With the development of the fluorescent [Ca2+] indicator dyes quin2, fura-2 and indo-1, increases in [Ca2+]. have been observed in endothelial cells from bovine or porcine aortae or from human umbilical vein in response to histamine, bradykinin, thrombin, adenine nucleotides and PAF. Furthermore, recent work has shown that these mediator-evoked rises in [Ca2+]i are both sufficient and necessary for the production and release of PGI2 (Hallam et al., 1988c). Our attention has now focussed on the mechanisms of Ca2+ movement and the sources of trigger Ca2+.
KeywordsEndothelial Cell Human Umbilical Vein Endothelial Cell Human Endothelial Cell Intracellular Store Calcium Ionophore A23187
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