Effects of exercise trainig and long-Term Survival in the BIO 14.6 cardiomyopathic Hamsters with chronic heart failure.

点击翻译按钮获取中文摘要

Background. Although exercise training improves prognosis of ischemic heart failure, the effects on nonischemic heart failure are still unclear even in animal models. Because of metabolic bulnerability to sympathetic stimulation of failing hearts, exercise training may adversely affect the prognosis of nonischemic heart failure despite the beneficial effects on exercise capacity. To test the hypothesis, we examined the effect of exercise training with or without beta-blocker therapy on exercise capacity and prognosis of cardiomyopathic hamsters. Methods. We assigned 87 BIO 14.6 hamsters at 30 weeks of age into 3 groups ; sedentary control group (group C, n=27), exercise training group (group Ex, n=30), and exercise training plus beta-blocker group (group ExB, n=29). On Day 1 of the study, baseline treadmill exercise was performed to determine the maximal running speed at which animals could catch up. On Day 2, exercise training and medication were started. Treadmill exercise for 25 min … More at 40% of the baseline maximal speed was performed on every week days for 160 days in groups Ex and ExB.In group ExB, metoprolol of 1mg/kg/day, a cardioselective beta_1-blocker, was orally administered during the study. To assess exercise capacity, the maximal treadmill exercise was performed on Day 30 and Day 90. The survival rate was assessed . Results. The maximal treadmill speed gradually decreased in groups C and ExB.However, the initial decrease on Day 30 was not observed in group Ex, suggesting a short-term benefits of exercise training on exercise capacity. In contrast, the survival rate was lower throughout the study in group Ex than in group C (Kaplan-Meier, p<.01). This effect was partly but significantly attenuated in group ExB (p<.005). The survival rate on Day 160 was 77% in group C, 51% in group ExB, and only 33% in group Ex. Conclusion. Despite short-term benefits on exercise capacity, exercise training aggravated prognosis of cardiomyopathic hamsters. This effect was attenuated by cardioselective beta_1-blockade. Our results suggest that long-term exercise training promotes the progression of cardiomyopathy via Beta_1-adrenergic stimulation. Less