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 Km value for l‐arginine transport was not different in patients compared with control subjects, while Vmax was significantly decreased in patients compared with controls. Moreover, agonists able to mobilize Ca2+ produced a further decrease in the l‐arginine uptake in controls and in patients, suggesting that Ca2+ intracellular levels down‐regulate l‐arginine transport in platelets from both control subjects and patients. Data suggest that drugs designed to control intracellular Ca2+ might restore platelet function in diabetic patients.