Effects of magnesium sulphate on leptin-dependent platelet aggregation: an ex vivo study.

Magnesium sulphate has well known antiplatelet properties. Its effect on leptin-dependent platelet aggregation has not been studied previously. Thus, we performed this ex vivo study to investigate whether magnesium sulphate is able to inhibit leptin-dependent aggregation of human platelets. We obtained platelet rich plasma (PRP) from venous blood samples of 16 healthy male volunteers, and we measured ADP-induced platelet aggregation in the presence of leptin alone (5-500 ng/mL) or leptin and magnesium sulphate (0.25-8 mM). Platelet pre-incubation with leptin led to a significant and dose-dependent increase in ADP-induced platelet aggregation. Magnesium sulphate was able to inhibit the pro-aggregating effect of leptin in a dose-dependent manner. The inhibitory effect was apparent at 1 mM of magnesium sulphate concentration (% maximal aggregation=38.1 +/- 12.2) and reached its maximum at 8 mM (% maximal aggregation=20.0 +/- 7.8). Our results demonstrate that leptin-dependent platelet aggregation is inhibited by magnesium sulphate in a dose-dependent manner. It seems conceivable that the blocking of hydrolysis of phosphoinositide and of intracellular calcium mobilization by magnesium sulphate may be involved in these findings.