title: Inhibitory action of cyclic AMP on inositol 1,4,5-trisphosphate-induced Ca2+ release in saponin-permeabilized platelets.
abstract: Ca2+ release triggered by inositol 1,4,5-trisphosphate (IP3) has been measured in saponin-permeabilized human platelets with quin2 or 45Ca2+. Ca2+ was sequestered by intracellular organelles in the presence of ATP, and IP3 released half of the sequestered Ca2+. The addition of cyclic AMP (cAMP) to permeabilized platelets transiently accelerated Ca2+ sequestration, but did not alter the steady-state level. In contrast, IP3-induced Ca2+ release was greatly inhibited by cAMP. Phorbol myristate acetate, an activator of protein kinase C did not affect IP3-induced Ca2+ release. These results indicate that cAMP may be involved in the regulation of IP3-induced Ca2+ release in human platelets.
authors.affiliation: Department of Biochemistry, Gifu University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tohmatsu
authors.forename: A
authors.initials: A
authors.lastname: Nishida
authors.forename: S
authors.initials: S
authors.lastname: Nagao
authors.forename: S
authors.initials: S
authors.lastname: Nakashima
authors.forename: Y
authors.initials: Y
authors.lastname: Nozawa
mesh_terms: D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology*; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D012503:Saponins / Q000494:pharmacology*; D013403:Sugar Phosphates / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D007295:Inositol Phosphates; D012503:Saponins; D013403:Sugar Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D002118:Calcium