The Effects Of Protein Kinase A Activation On Platelets Aggregation

[Objective]To investigate the effects of protein kinase A(PKA)activation on agonists-induced platelets aggregation in vitro.[Methods]Washed platelets were collected from peripheral blood of healthy adult volunteers.The platelets were preincubated with the PKA activator forskolin in vitro.The platelets aggregation was induced by platelet agonist U46619,collagen,thrombin,ristocetin and ADP,respectively.The platelets aggregation was measured by platelets aggregator,and the platelet PKA phosphorylation substrate(GP Ⅰbβ serl66)and total PKA activity were determined by western blot and ELISA,respectively.[Results]Compared with the DMSO-treated platelets in the control group,the total PKA activity of platelets were increased(p<0.05)by U46619,Collagen,Ristocetin and ADP treatment,respectively.In contrast,the total PKA activity of platelets were decreased by thrombin treatmen(p<0.05).Compared with the controls,5 μmol/L forskolin significantly inhibited U46619,ADP and collagen-induced platelets aggregation(p<0.001);and had mild inhibiting effects on thrombin-induced platelets aggregation(p<0.05).2.5 μmol/L forskolin significantly inhibited U46619 and collagen-induced platelets aggregation(p<0.001);and had gentle inhibiting effects on ADP-induced platelets aggregation(p<0.05);but had limited effects on thrombin-induced platelets aggregation(p>0.05).2.5-10μmol/L forskolin had little effect on ristocetin-induced platelets aggregation(p>0.05).10 μmol/L forskolin significantly inhibited U46619,collagen,ADP and collagen-induced platelets aggregation(p<0.001).[Conclusion]Protein kinase A(PKA)activity was increased in platelets induced by U46619,Collagen,Ristocetin and ADP.Hyperactivation of PKA inhibits agonists-induced the platelets aggregation.Protein kinase A is involved in platelet aggregation induced by agonists including U46619,Collagen,Thrombin and ADP.