Nitric oxide as a modulator in platelet- and endothelium-dependent antithrombotic effect of eplerenone in diabetic rats.

We have recently demonstrated the antithrombotic effect of eplerenone on the arterial thrombotic process in diabetic rats associated with suppression of coagulation and enhancement of fibrinolysis. The aim of this study was to evaluate the role of platelets and endothelium in the mechanism of eplerenone antithrombotic action. Diabetes was induced in male Wistar rats with a single injection of streptozotocin (65 mg/kg). On the 25th day, treatment with eplerenone (100 mg/kg) was initiated for 10 days. Eplerenone did not change hemodynamic parameters (blood pressure, carotid blood flow, and heart rate), however, improved endothelium-dependent vasorelaxation in aortas and small mesenteric arteries, enhanced the aortic amounts of mRNA of endothelial nitric oxide synthase (eNOS), and reduced mRNA of nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase 2. A prolongation of bleeding time and decrease in platelet adhesion to collagen ex vivo was also observed. These changes were accompanied by prolonged time to occlusion and increased blood flow, and finally reduced thrombus mass in diabetic rats. The inhibition of NOS with L-NAME reduced the eplerenone antithrombotic effect. Our study provides evidence that the antithrombotic effect of eplerenone in diabetic rats is nitric oxide-dependent and associated with inhibiting the adhesion of platelets, as well as normalizing endothelial function. The mechanism of eplerenone antithrombotic action in diabetes is a result of improved endothelial nitric oxide bioavailability that leads to the improvement vascular and platelet function.