EFFECTS OF CHRONIC EXERCISE ON RENAL FUNCTION IN RATS WITH CHRONIC RENAL FAILURE

Abstract

346 Exercise training, which has some potential for improving cardiovascular and metabolic disorders, is beneficial in the treatment of many chronic disease states including ischemic heart disease, hypertension, diabetes mellitus, and hyperlipidemia. In contrast, acute exercise causes proteinuria and subsequent reductions in both renal blood flow and glomerular filtration rate. The quantity of urinary excretion is known to correlate closely with the extent of histological injury of the glomeruli. The patients with chronic renal failure are restricted to mild exercise and tend to lack of exercise. However, there have been few reports regarding the chronic influence of exercise on the progression of renal disease. Therefore we assessed the renal effects of mild to severe chronic treadmill exercise in the spontaneously hypertensive rats (SHR) remnant kidney model of chronic renal failure (CRF). Eight-week-old SHR were subjected to 5/6 nephrectomy by removal of the left kidney and infarction of two-thirds of the right kidney. The rats were divided into 4 groups: a) no treadmill running (No-Ex); b) mild Ex (20m/min for 30 min) (L-Ex); c) moderate Ex (20m/minfor 60 min) (M-Ex); d)severe Ex (35m/min for 60 min) (S-Ex) 5 times/week for 4 weeks. In SHR-CRF, systolic blood pressure, heart weight, urinary protein excretion, blood urea nitrogen, and serum creatinine level all increased significantly when compared with those of sham-operated SHR. Chronic treadmill exercise significantly attenuated the increase in proteinuria (p<0.01) and in serum total cholesterol levels (p<0.05) intensity-dependently. These results were confirmed by morphological analysis of the kidneys in each group of rats. Ex (especially M-Ex) significantly and effectively protected against increases in the percentage of focal glomerular sclerosis. These results indicate that exercise does not worsen renal function and suggest that exercise have renal-protective actions in this model of rats.