Abstract
Propolis is increasingly used as a dietary supplement in Japan. In this study, the effects of two types of Brazilian propolis (Pro-Ba and Pro-Bb) and Chinese propolis (Pro-C) on the cardiovascular function of male Wistar rats, which were fed ad libitum a Pro-Ba, Pro-Bb and Pro-C diet for 4 weeks, were examined. Pro-Ba was obtained from the Alecrim forest in Brazil and Pro-Bb was obtained from another forest in Brazil. Pro-C was obtained in China. After being fed them for 4 weeks, the liver, spleen, thymus, blood, atria and aorta were isolated from rats. The propolis diet did not change the body weight, liver weight, spleen weight, heart rate or blood pressure. Although, feeding with Pro-Ba and Pro-Bb significantly increased the ratio of thymus weight per 100 g body weight, Pro-C did not. Leucocytes, erythrocytes, hemoglobin, hematocrit and platelets were unaltered by feeding with any of the propolis diets. Isoproterenol-induced positive and acetylcholine-induced negative inotropic and chronotropic effects on the atria were not affected by any of the propolis diets. Acetylcholine and sodium nitroprusside-induced relaxation of the aortic rings was also not affected by the propolis diets. In in vitro experiments, Pro-Ba and Pro-Bb (1.0 mg/ml) significantly increased the beat rate of the atria isolated from the rats. On the other hand, Pro-C (1.0 mg/ml) significantly decreased the beat rate. In addition, Pro-Ba, Pro-Bb and Pro-C (0.1-3.0 mg/ml) produced a dose-dependent relaxation in the aortic ring precontracted with noradrenaline.
