ATP depletion in human platelets caused by permeabilization with saponin does not prevent serotonin secretion induced by collagen.
Saponin (5 to 25 micrograms/ml) produced a concentration-dependent decrease in the cellular content of total ATP and [32P]ATP in 32P-labeled human platelets. In platelets whose ATP had been profoundly decreased by saponin, Ca2+ produced phosphomonoesteratic cleavage of the polyphosphoinositides with a concomitant accumulation of phosphatidylinositol. Collagen still induced secretion of serotonin in platelets that had been treated with saponin in the presence or absence of Ca2+. This effect of collagen occurred in the absence of the formation of cyclooxygenase metabolites. In platelet permeabilized with saponin, agonist-induced secretion and aggregation seems to be unrelated to protein phosphorylation, breakdown of the inositol phospholipids by phospholipase C and formation of cyclooxygenase metabolites.
D000255:Adenosine Triphosphate / Q000097:blood*; D000328:Adult; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D003094:Collagen / Q000494:pharmacology*; D006801:Humans; D008875:Middle Aged; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000097:blood; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D012503:Saponins / Q000494:pharmacology*; D012701:Serotonin / Q000097:blood*
D001095:Arachidonic Acids; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D012503:Saponins; D016718:Arachidonic Acid; D012701:Serotonin; D000255:Adenosine Triphosphate; D003094:Collagen; D011451:Prostaglandin-Endoperoxide Synthases; D002118:Calcium