Abstract
Recently, roles of cyclic AMP and cyclic GMP in platelets have been getting important on mechanisms of platelet aggregation. However, behaviours of c-AMP and c-GMP phosphodiesterase (PDE) in platelet aggregation are still unknown. So relationships between activities of c-AMPPDE and c-GMPPDE in platelets and platelet aggregability induced by ADP and adrenaline were observed using 57 human materials. Activities of c-AMPPDE and c-GMPPDE were measured by Hidaka and Shibuya method (Biochem. Med. 10: 301, 1974). Using the same samples, platelet aggregabilities induced 3 and 10μM ADP and 0.1 and 1μg/ml of adrenaline were measured by an optical density method. In a platelet aggregation curve, slope of the curve and intensities of primary aggregation and aggregation at 5 minutes after the addition of reagent were measured. In 16 cases, screen filtration pressures (SFP) induced by 3μM ADP were also measured.
Activities of c-AMPPDE and c-GMPPDE of platelets were 1.17-8.36 and 4.16-24.39pmol/min/107 platelets respectively. These means and standard errors were 3.92±0.26 and 11.97±0.89pmol/min/107 platelets respectively. There were statistically significant correlations between slope induced by 10μM ADP and c-AMPPDE or c-GMPPDE activities respectively (p<0.001). These correlation coefficients (r) were 0.31 on c-AMPPDE and 0.48 on c-GMPPDE activities. Also a significant correlation between an activity of c-GMPPDE and an intensity of primary aggregation induced by 10μM ADP (r=0.28, p<0.05). Using 1μg/ml of adrenaline, there was a significant negative correlation between an activity of c-GMPPDE and an ntensity of 5 minutes aggregation (r=-0.38, p<0.01). SFP showod a significant negative correlation to a c-GMPPDE activity (r=-0.520, p<0.05). These results suggest important roles of c-AMPPDE and c-GMPPDE activities of platelets on platelet aggregation.
