Increased platelet thromboxane receptor sensitivity in diabetic patients with proliferative retinopathy

Platelet aggregation to collagen in 12 Type 1 (insulin-dependent) diabetic patients with background retinopathy and 12 Type 1 diabetic patients with proliferative retinopathy was compared with an age- and sex-matched control group. An analogue of prostaglandin H2, 11,9 epoxymethano-prostaglandin H2, which directly stimulates thromboxane receptors, and EP 092, which is a competitive thromboxane A2 receptor antagonist, were used to investigate changes at platelet thromboxane receptor level in these groups. The concentration of collagen (EC50) required to give 50% of maximum aggregation did not differ between the two diabetic groups and the control group. However, platelets from the proliferative retinopathy group were significantly more sensitive to the thromboxane mimetic (11,9 epoxymethano-prostaglandin H2) (p less than 0.005) than the background retinopathy and control groups. This change may be a factor in the development of proliferative retinopathy.