Increased Platelet Aggregation and Decreased Sensitivity of Platelets to Synthesized Prostacyclin in Alloxan-Diabetic Rabbits

Abstract

Platelet aggregation and sensitivity of platelets to prostacyclin were examined with a view to clarify platelet function in alloxan-diabetic rabbits. Diabetic rabbits were obtained by intravenous injection of alloxan (100mg/ kg body weight) and range of plasma glucose in these diabetic rabbits was 350-500mg/100ml. Blood was collected from the central artery of the ear of normal and alloxan- diabetic rabbits. Platelet aggregation was measured turbidometrically as rate of light transmission at maximal aggregation to light transmission of platelet poor plasma by a NKK aggregometer (Tokyo, Japan). Platelet aggregation was induced by ADP with each final concentration of 0.5, 1.0, 2.0 and 6.0 μM. Sensitivity of platelets to synthesized prostacyclin (Ono Pharma. Co., Tokyo, Japan) was represented as prostacyclin concentration of fifty percent inhibition of ADP-induced platelet aggregation.Platelet aggregation rate in normal and alloxan-diabetic rabbits was as follows; 8.4±1.0, 22.8±2.6%(0.5 μM), 22.3±1.5, 35.2±3.5%(1.0 μM), 37.1±1.7,50.0±2.6%(2.0 μM), 51.0±2.2, 66.7±7.0%(6.0 μM ADP)(Mean±S.E., P< 0.005). Prostacyclin concentration of fifty percent inhibition of ADP-induced platelet aggregation in normal and alloxan- diabetic rabbits was as follows; 42.37±1.68, 48.50±0.48 ng/ml (Mean±S.E., P< 0.01).In conclusion, platelets of alloxan-diabetic rabbits presented a significant decrease in sensitivity to synthesized prostacyclin as compared to platelets from normal rabbits, with a significant increase in ADP-induced platelet aggregation.