Summary
Although roles of cyclic AMP and cyclic GMP in platelets are thought to be important on platelet aggregation, little information on their phosphodiesterase (PDE) is available. Cyclic AMP and cyclic GMP hydrolytic activities of platelets (cAMPPDE and cGMPPDE in platelets) and platelet aggregation by ADP and adrenaline were measured in 22 healthy volunteers, 26 arteriosclerotic patients and other 20 miscellaneous patients excluding vascular diseases. Activities of cAMPPDE and cGMPPDE of platelets were 2.37±0.52, 7.23 ± 1.84 in the healthy, 2.50±0.85, 7.53±2.60 in the arteriosclerotics and 2.38± 1.02, 6.98±2.59 pmol/min/107 platelets in the miscellaneous patients, respectively. No significant difference was observed among these three groups. Platelet aggregabilities also showed no significant difference. However, there was a significant inverse correlation between the aggregability by 1 μg/ml of adrenaline and the PDE activities only in the arteriosclerotic patients. The correlation coefficients were −0.61 between the primary aggregation and cAMPPDE,−0.65 between the primary aggregation and cGMPPDE, −0.58 between the 5 min aggregation and cAMPPDE and −0.76 between the 5 min aggregation and cGMPPDE. The inverse correlation between platelet aggregation and cyclic nucleotide metabolism in circulating platelets of the arteriosclerotic patients may suggest that interaction of platelets with arteriosclerotic vessel walls would produce a certain change in platelets.
