Modification of Na+/H+ exchanger in human platelets by 1,2-dioctanoylglycerol, a protein kinase C activator.
Protein kinase C activation in human platelets has a modulatory role in maintaining intracellular pH (pHi), by adjusting pHi at a particular value (7.22). Changes in pHi induced by protein kinase C appeared to be dependent upon the difference between H+ efflux catalyzed by the Na+/H+ exchanger and H+ production. The pHi recovery after acid loading was significantly facilitated by protein kinase C activation. Analysis of the rate constant for pHi recovery suggested that the turnover rate or the apparent affinity of the Na+/H+ exchanger for H+ was increased. Protein kinase C also decreased the Km value of the Na+/H+ exchanger for extracellular Na+. Thus, it is suggested that the role of protein kinase C in platelet pHi regulation is dual, adjusting the pHi value at a certain setpoint on the one hand, and increasing the rate constant of the Na+/H+ exchanger on the other.
Ozaki
Y
Y
Department of Clinical and Laboratory Medicine, Yamanashi Medical College, Japan.
Matsumoto
Y
Y
Yatomi
Y
Y
Higashihara
M
M
Kume
S
S
D000143:Acids / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects*; D002352:Carrier Proteins / Q000097:blood* / Q000187:drug effects*; D003593:Cytoplasm / Q000187:drug effects; D004075:Diglycerides / Q000494:pharmacology*; D004789:Enzyme Activation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011422:Propionates / Q000494:pharmacology; D011493:Protein Kinase C / Q000187:drug effects*; D017923:Sodium-Hydrogen Exchangers
D000143:Acids; D002352:Carrier Proteins; D004075:Diglycerides; D011422:Propionates; D017923:Sodium-Hydrogen Exchangers; C044295:1,2-dioctanoylglycerol; D011493:Protein Kinase C; C029658:propionic acid