PLATELET SENSITIVITY INVITRO TO ADENOSINE-5'-DIPHOSPHATE AND PROSTACYCLIN AND DIABETIC-RETINOPATHY

Platelet sensitivity to ADP and prostacyclin in diabetes has been assessed using collision theory and the concept of sticking probability (the probability of particle union). Twenty Type 1 (insulin-dependent) diabetic men (10 with no or minimal retinopathy and a matched group of 10 with proliferative retinopathy) and 10 age-matched non-diabetic men were studied. Platelets from the 20 diabetic patients required, on average, 37% less ADP to achieve a sticking probability of 0.5 (ED50) compared with platelets from the non-diabetic subjects (medians 1.50 and 0.95 .mu.mol/l, respectively; P < 0.01). The platelet prostacyclin response was assessed by the Ki for inhibition of ADP-induced aggregation. Platelets from the diabetic patients had similar prostacyclin sensitivity to those from the non-diabetic subjects (medians 0.42 and 0.42, respectively). Diabetic patients with and without retinopathy had similar platelet sensitivity to both ADP and prostacyclin.