Impaired L-arginine uptake in platelets from type-2 diabetic patients

The L-arginine uptake of resting platelets from type-2 diabetic patients and control subjects was measured and the kinetic parameters defined. The effect of platelet stimulation with agonists was also investigated. Kinetic studies showed that the K(m) value for L-arginine transport was not different in patients compared with control subjects, while V(max) was significantly decreased in patients compared with controls. Moreover, agonists able to mobilize Ca(2+) produced a further decrease in the L-arginine uptake in controls and in patients, suggesting that Ca(2+) intracellular levels down-regulate L-arginine transport in platelets from both control subjects and patients. Data suggest that drugs designed to control intracellular Ca(2+) might restore platelet function in diabetic patients.