Effect of exercise training on renal function and renal aquaporin-2 expression in rats with chronic heart failure

Chronic heart failure (CHF) is often accompanied by renal dysfunction. Exercise training may relieve the symptomatic burden and improve the overall prognosis of CHF. In the present study, the effects of exercise training on renal function and renal aquaporin (AQP)-2 expression in CHF rats were examined to determine whether exercise training could relieve renal dysfunction in CHF rats. Male Sprague-Dawley rats were divided into three groups: sham, sedentary CHF (Sed-CHF) and exercise training CHF (Ex-CHF) groups. Cardiorenal function was assessed in each group by haemodynamic measurement and ultraviolet spectrophotometry. Pathological changes in cardiac and renal tissues were evaluated histologically and the collagen volume fraction (CVF) was calculated. The expressions of AQP-2 and β-tubulin were determined by western blotting and immunohistochemistry. The Sed-CHF rats were found to have increased left ventricular end-diastolic pressure (LVEDP) and CVF in the heart compared with sham rats. Exercise training decreased LVEDP and CVF values in Ex-CHF rats. The Sed-CHF rats were found to have increased serum levels of creatinine (sCr), blood urea nitrogen (BUN) and arginine vasopressin (AVP), as well as increased CVF in the kidney, compared with sham rats. Exercise training decreased levels of sCr, BUN, AVP and CVF in Ex-CHF rats. Moreover, exercise training decreased AQP-2 and β-tubulin protein expression in the kidney of CHF rats. The results suggest that exercise training can significantly improve the renal dysfunction in CHF rats and that the underlying mechanism may be related to water reabsorption and preventing changes to the cytoskeleton.