Characteristics of collagen-induced Ca2+ mobilization in bovine platelets.
We characterized the collagen-induced increase in cytosolic Ca2+ ([Ca2+]i) of bovine platelets loaded with the Ca2+ indicator Fura-PE3/AM. Collagen (10 micrograms/ml)-induced increase in [Ca2+]i was only partially inhibited by aspirin, a cyclooxygenase inhibitor, or adenosine 3'-phosphate 5'-phosphosulfate (A3P5PS, a P2Y1 receptor antagonist), while in human platelets it was almost completely suppressed by aspirin. Collagen-induced increase in [Ca2+]i of bovine platelets was inhibited by U73122 (0.3-5 microM), a phospholipase C inhibitor. Collagen (10 micrograms/ml) increased production of inositol 1,4,5-trisphosphate, which was prevented by pretreatment with U73122 (5 microM). Collagen (10 micrograms/ml) accelerated Mn2+ entry, since the rate of Fura-PE3 quenching by Mn2+ was enhanced by 13-fold following stimulation with collagen. U73122 inhibited the acceleration of Mn2+ entry induced by collagen. PGE1 (2.5 microM) partially inhibited the collagen (50 micrograms/ml)-induced increase in [Ca2+]i in bovine platelets but not in human platelets. The data suggest that collagen-induced Ca2+ mobilization in bovine platelets is mediated by phospholipase C. The Ca2+ mobilization in bovine platelets is different from that in human ones as to the dependency on arachidonic acid metabolites and sensitivity to PGE1.
Shiraishi
M
M
Department of Veterinary Pharmacology, Miyazaki University, Japan.
Ikeda
M
M
Fujishiro
T
T
Fukuyama
K
K
Ito
K
K
D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D003094:Collagen / Q000378:metabolism / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000032:analysis; D016257:Fura-2 / Q000031:analogs & derivatives / Q000032:analysis; D006801:Humans; D008345:Manganese / Q000493:pharmacokinetics; D010724:Phosphoadenosine Phosphosulfate / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D004963:Estrenes; D005456:Fluorescent Dyes; D010975:Platelet Aggregation Inhibitors; D011760:Pyrrolidinones; C098106:fura-PE3; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D016718:Arachidonic Acid; D008345:Manganese; D010724:Phosphoadenosine Phosphosulfate; D004533:Egtazic Acid; D000244:Adenosine Diphosphate; D019284:Thapsigargin; D003094:Collagen; D010738:Type C Phospholipases; D013917:Thrombin; D001241:Aspirin; D002118:Calcium; D016257:Fura-2