title: The cytoplasmic concentration of free calcium in platelets is controlled by stimulators of cyclic AMP production (PGD2, PGE1, forskolin).
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+.
mesh_terms: D000527:Alprostadil; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D055598:Chemical Phenomena; D002621:Chemistry; D005576:Colforsin; D000242:Cyclic AMP / Q000096:biosynthesis*; D003593:Cytoplasm / Q000378:metabolism; D004224:Diterpenes / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D015230:Prostaglandin D2; D011453:Prostaglandins / Q000494:pharmacology*; D011457:Prostaglandins D / Q000494:pharmacology*; D011458:Prostaglandins E / Q000494:pharmacology*; D013050:Spectrometry, Fluorescence
chemical_list: D004224:Diterpenes; D011453:Prostaglandins; D011457:Prostaglandins D; D011458:Prostaglandins E; D005576:Colforsin; D000242:Cyclic AMP; D000527:Alprostadil; D015230:Prostaglandin D2; D002118:Calcium