Effect of cytoplasmic pH on platelet activation by arachidonic acid.
The effects of cytoplasmic acidification by nigericin, monovalent cation ionophore, on platelet activation induced by arachidonic acid (AA) were examined. AA-induced aggregation and TXB2 formation were inhibited with decreasing cytoplasmic pH (pHc). Although TXA2 receptor agonists (STA2, U-46619)-induced aggregation of some platelet samples were suppressed by nigericin, the suppression did not correspond to the acidification of pHc. Aggregation initiated by collagen was inhibited by nigericin. The inhibition, however, was not observed in platelets treated by aspirin. These results suggest that the inhibition of AA-induced aggregation by cytoplasmic acidification is due to inhibition of the metabolism of AA to TXA2.
Ishikawa
Y
Y
Japanese Red Cross Central Blood Center, Tokyo.
Ogawa
A
A
Sasakawa
S
S
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001095:Arachidonic Acids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects*; D003094:Collagen / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors; D003593:Cytoplasm / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D009550:Nigericin / Q000494:pharmacology*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D013929:Thromboxane B2 / Q000096:biosynthesis
D000900:Anti-Bacterial Agents; D001095:Arachidonic Acids; D016861:Cyclooxygenase Inhibitors; D010975:Platelet Aggregation Inhibitors; D013929:Thromboxane B2; D003094:Collagen; D009550:Nigericin