Carvedilol and Pycnogenol® improve the function of diabetic hearts in rats

Abstract

Abstract We observed the changes in electrical activity, biometric and haemodynamic parameters of hearts in animals with experimental diabetes mellitus (DM). As well the effect of carvedilol, PycnogenolR and its combination with carvedilol on DM heart function was tested. DM was induced by streptozotocin over three sequential days at a dose of 25 mg/kg body weight i.p. We started therapy by suspension of carvedilol, PycnogenolR and their combination for six weeks. Blood pressure was measured using tail cuff plethysmography. ECG, haemodynamic and biometric parameters were measured in isolated hearts perfused according to the Langendorff. DM rats had increased systolic arterial blood pressure, thicker free wall of left ventricle but weakened myocardial contractility compared with controls. In contrast to controls, electrophysiological parameters showed prolonged QT interval and increased incidence of dysrhythmias in DM rats. The PycnogenolR administration induced regression of left ventricular hypertrophy, improved left ventriculi contraction and increased coronary flow; however, it did not improve the electrical activity of the myocardium compared with DM ones. Carvedilol also reversed the myocardial remodelling, shortened the duration of QT interval and suppressed the incidence of dysrhythmias. The common combination of drugs improved biometric and haemodynamic parameters compared with DM animals, however, not so significantly as monotherapy. On the other hand, the combination of carvedilol and PycnogenolR significantly reduced the duration of the QT interval and shortened the incidence of dysrhythmias. We can conclude that the administration of PycnogenolR effectively improved haemodynamic parameters, and carvedilol affected biometric parameters and also electrical parameters in DM animals. We observed the marked synergic effect of the combination of both drugs on the electrical activity of myocardium. This combination shortened the most pathologically prolonged QT interval and reduced the number of dysrhythmias.