Platelet activating factor-induced P-selectin expression in platelets and its related signal transduction

AIM: To study the intracellular signal transduction mechanisms of platelet activating factor (PAF)-induced platelet P-selectin expression. METHODS: Human blood platelets were used to test the effect of PAF-induced P-selectin expression using flow cytometry. RESULTS: PAF 20 nmol.L-1 elicited a moderate upregulation of P-selectin expression [(47.5 +/- 1.3) % vs control (3.8 +/- 0.9) %, P < 0.01]. Pretreatment with egtazic acid (EGTA) 2 mmol.L-1 and 5,5'-dimethyl-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetracetic acid (BAPTA) 200 mu mol.L-1 to block Ca2+ influx or chelate the intracellular calcium, respectively, reduced P-selectin expression in response to PAF [(13.3 +/- 0.9) % and (16.8 +/- 1.9) % vs (47.5 +/- 1.3) % of PAF group, P < 0.01]. Inhibition of Na+/H+- exchange with amiloride (Ami) 400 mu mol. L-1 resulted in an inhibition of P-selectin expression [(37.5 +/- 2.1) % vs (47.5 +/- 1.3) % of PAF group, p <0.01]. Genistein (Gen) 300 mu mol.L-1 to inhibit protein tyrosine phosphorylation showed similar effect [(29 +/- 4) % vs (47.5 +/- 1.3) % of PAF group, P < 0.01]. CONCLUSION: Multiple signal transduction pathways, including protein tyrosine phosphorylation, Na+/H+ exchange, and Ca2+ mobilization, mediated PAF-induced P-selectin expression.