Inhibition of nitric oxide biosynthesis promotes P-selectin expression in platelets. Role of protein kinase C.
Inhibition of NO synthesis promotes P-selectin expression on endothelial cells; however, the precise mechanism is unclear. Because No has been shown to inhibit protein kinase C (PKC) activity, we examined the hypothesis that the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) stimulates P-selectin expression on platelets via PKC activation. Ten-minute incubation with either phorbol 12-myristate 13-acetate (PMA), thrombin, or L-NAME significantly increased P-selectin expression on platelets (as assessed by flow-cytometric analysis) and PKC activity of platelet membranes. Increased P-selectin expression induced by either PMA, thrombin, or L-NAME was significantly attenuated by the selective PKC inhibitor UCN-01 (7-hydroxystaurosporine). Furthermore, L-NAME-induced P-selectin expression was significantly attenuated by either L-arginine, 8-bromo-cGMP, or sodium nitroprusside (SNP). Interestingly, L-NAME further potentiated P-selectin upregulation by thrombin. L-NAME, thrombin, and PMA also significantly increased polymorphonuclear leukocyte adherence to the coronary artery endothelium, an effect that was significantly attenuated by the anti-P-selectin monoclonal antibody PB1.3 or by UCN-01, L-arginine, 8-bromo-cGMP or SNP but not by D-arginine or he nonblocking anti-P-selectin monoclonal antibody NBP1.6. These results indicate that inhibition of NO synthesis induces rapid P-selectin expression, which appears to be at least partially mediated by PKC activation in platelets. Similar effects and mechanisms of L-NAME on P-selectin function were also observed in endothelial cells, another site of P-selectin expression.
Murohara
T
T
Department of Physiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pa, 19107-6799, USA.
Parkinson
S J
SJ
Waldman
S A
SA
Lefer
A M
AM
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001792:Blood Platelets / Q000378:metabolism*; D002415:Cats; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D019007:P-Selectin / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000378:metabolism*
D004791:Enzyme Inhibitors; D019007:P-Selectin; D009569:Nitric Oxide; D001120:Arginine; D011493:Protein Kinase C; D019331:NG-Nitroarginine Methyl Ester