Na+/H+ exchange is not necessary for protein kinase C-mediated effects in platelets.
The role of Na+/H+ exchange in protein kinase C-mediated effects in platelets was investigated by studying the effect of removal of extracellular Na+ ([Na+]e) on the different responses induced by phorbol 12-myristate 13-acetate (PMA) and 1,2-dioctanoylglycerol (diC8). None of the responses studied, namely, protein phosphorylation, translocation of enzyme activity to the membrane fraction, potentiatory and inhibitory effect on platelet activation ([Ca2+]i, arachidonate and granule release) showed an absolute dependence on [Na+]e. With the exception of dense-granule release, which was clearly potentiated by the removal of [Na+]e and showed a negative correlation with exchanger activity, the other effects of PMA and diC8 were not affected by [Na+]e removal. It is concluded that Na+/H+ exchange is not essential for protein kinase C activation in platelets.
Krishnamurthi
S
S
Thrombosis Research Unit, Rayne Institute, King's College School of Medicine and Dentistry, London, England.
Patel
Y
Y
Morgan
W A
WA
Wheeler-Jones
C P
CP
Kakkar
V V
VV
D001345:Autoradiography; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D002352:Carrier Proteins / Q000378:metabolism*; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011506:Proteins / Q000032:analysis; D012701:Serotonin / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D001620:beta-Thromboglobulin / Q000378:metabolism
D002352:Carrier Proteins; D004075:Diglycerides; D011506:Proteins; D017923:Sodium-Hydrogen Exchangers; D001620:beta-Thromboglobulin; C044295:1,2-dioctanoylglycerol; D012701:Serotonin; D012964:Sodium; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate