The influence of activating hormones on human platelet membrane Ca2+-ATPase activity.
Intact platelets were pretreated with hormones and thereafter membranes were prepared and Ca2+-ATPase activity determined. Thrombin decreased the Vmax of Ca2+-ATPase after pretreatment of intact platelets. Platelet activating factor, vasopressin and ADP also decreased Ca2+-ATPase activity. 12-O-tetradecanoylphorbol-13-acetate (TPA) or A23187 or ionomycin alone had no effect, whilst the simultaneous pretreatment with TPA and Ca2+-ionophore decreased Ca2+-ATPase activity. cAMP elevating agents prostaglandin E1 (PGE1) and forskolin had no influence per se on Ca2+-ATPase, but antagonized the inhibitory effect of thrombin. The data suggest a close connection between phosphoinositide metabolism and the Ca2+-ATPase system.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000527:Alprostadil / Q000494:pharmacology; D001792:Blood Platelets / Q000201:enzymology*; D000001:Calcimycin / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000097:blood*; D002462:Cell Membrane / Q000201:enzymology; D005576:Colforsin / Q000494:pharmacology; D004987:Ethers / Q000494:pharmacology; D006801:Humans; D015759:Ionomycin; D007700:Kinetics; D010972:Platelet Activating Factor / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology
D004987:Ethers; D010972:Platelet Activating Factor; D014667:Vasopressins; D005576:Colforsin; D000001:Calcimycin; D015759:Ionomycin; D000244:Adenosine Diphosphate; D013917:Thrombin; D000252:Calcium-Transporting ATPases; D000527:Alprostadil; D013755:Tetradecanoylphorbol Acetate