The cytoplasmic concentration of free calcium in platelets is controlled by stimulators of cyclic AMP production (PGD2, PGE1, forskolin) |
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| Authors: | M B Feinstein J J Egan R I Sha'afi J White |
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| Institution: | 1. Department of Pharmacology, University of Connecticut Health Center, Farmington, CT 06032 USA;2. Department of Oral Biology, University of Connecticut Health Center, Farmington, CT 06032 USA;3. Department of Physiology, University of Connecticut Health Center, Farmington, CT 06032 USA |
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| Abstract: | Maximal stimulation of platelets with thrombin results in a rapid increase in cytoplasmic Ca2+ (from 0.1 microM to 1-3 microM), as measured with the fluorescent intracellular Ca2+ indicator Quin-2. Prior addition of the adenylate cyclase stimulators PGD2, PGE1 or forskolin inhibited the rise in cytoplasmic Ca2+. When added after the maximal response to thrombin was attained adenylate cyclase stimulators caused a rapid fall of cytoplasmic Ca2+ back to the original "resting" level. This effect coincides with the reversal of thrombin-induced, Ca2+-dependent protein phosphorylation, and cytoskeleton assembly. It is suggested that cAMP-dependent reactions maintain low levels of cytoplasmic Ca2+ by promoting transport and/or binding of Ca2+. |
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