[Contribution of sympathetic activation to antihypertrophic memory after regression of exercise-induced physiological myocardial hypertrophy in mice].

OBJECTIVE: To investigate whether anti-hypertrophic memory exists after regression of exercise-induced physiological myocardial hypertrophy (PMH) and explore the contribution of sympathetic activation to hypertrophic memory formation. OBJECTIVE: Seventy-two mice were randomized equally into 6 groups, including sedentary sham-operated group, exercise hypertrophic preconditioning (EHP) + sham operation group, bisoprolol (an adrenergic β1 receptor blocker) + EHP + sham operation group (biso+Exe+Sham group), sedentary group with transverse aortic constriction (TAC) (Sed+TAC group), EHP+ TAC group (Exe+TAC group), and bisoprolol+EHP+TAC group (biso+Exe+TAC group). The mice in the EHP groups were subjected to 3 weeks of swimming training, and in the bisoprolol groups, bisoprolol was administered by gavage once daily from two days before till the end of the training. One week after the training, TAC or sham surgery was performed. Echocardiography and hemodynamic measurements were performed to evaluate cardiac function of the mice, and the myocardial tissues were examined histologically to detect cardiac remodeling. OBJECTIVE: < 0.05) in Exe + TAC group than in Sed + TAC group. No significant difference was found in these parameters between biso + Exe + TAC group and Sed + TAC group. OBJECTIVE: Anti-hypertrophic memory exists even after the regression of exercise-induced PMH, which may be attributed to the activation of sympathetic nervous system during exercise.