Effects Of Exercise Training On Blood Pressure And It’s Relationship With Angiotensin-converting Enzyme2Expression In Central Nervoussystem Of Spontaneously Hypertensive Rats

Purpose1. To study effects of chronic aerobic exercise on blood pressure and arterial baroreflex sensitivity in spontaneously hypertensive rats (SHR).2. To detect the levels mRNA of angiotensin-converting enzyme2in central vascular system of SHR rats. To explore whether angiotensin converting enzyme2participates in the process that exercise training reduces blood pressure in the condition of hypertension.MethodThere are24male16–weeks-old rats. Spontaneously hypertensive rats and normal rats were randomly divided into normal quiet group (sedentary, Sed) and exercise training (ExT) groups, respectively: quiet control group, exercise control group, quiet group of hypertension, exercise group of hypertension, n=6. Exercise group rats ran on stage60minutes,18-20m/min,6days/week,8weeks in tatal. Blood pressure of rats of each group was measured once a week. During24hours after the exercise training, applying the femoral artery and vein cannulation and intravenous phenylephrine to test the baroreflex sensitivity. The distribution of angiotensin converting enzyme2expression in cerebral cortex, solitary tract nucleus, rostral ventrolateral and hypothalamus was detected using immunohistochemistry method. Angiotensin converting enzyme2mRNA expression levels were detected in cerebral cortex, solitary tract nucleus, rostral ventrolateral medulla and hypothalamus by quantitative real-time PCR.Result1. After exercise training, the blood pressure of normal rats had no apparent change. But the blood pressure of exercise group of hypertension decreased by17mmHg,(P＜0.05); and decreased by11mmHg as compared with that of quiet group of hypertension rats (P＜0.05).2. When compared with quiet group of hypertension rats, the baroreflexsensitivity of exercise group of hypertension rats improved significantly (P＜0.05). But the baroreflexsensitivity of normal rats had no apparent change.3. Angiotensin converting enzyme2distributed in the cerebral cortex, solitary tract nucleus, ventrolateral medulla, the hypothalamus. In the cortex, the angiotensin-converting enzyme2mRNA expression level decreased significantly in quiet group of hypertension when compared with that of quiet control group rats (P＜0.05); In hypothalamus and solitary tract nucleus, as compared with that of quiet group of hypertension rats, the angiotensin-converting enzyme2mRNA expression level of exercise group of hypertension rats was significantly increased(P＜0.05).ConclusionThe mechanism that exercise training significantly reduced blood pressure in spontaneously hypertensive rats may be improve arterial baroreflex function and increase the expression of brain angiotensin-converting enzyme2.