Effects of exercise training on nitric oxide synthase in the kidney of spontaneously hypertensive rats

Exercise training is known to have antihypertensive effects in humans and animals with hypertension, as well as to exhibit renal protective effects in animal models of hypertension and chronic renal failure. However, the mechanisms regulating these effects of exercise training remain unclear. The present study examined the effects of exercise training on nitric oxide synthase (NOS) in the kidneys of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Male SHR and WKY rats were randomly divided into a sedentary group and a treadmill exercise group for 8 weeks. Systolic blood pressure (SBP) was measured every 2 weeks by the tail-cuff method and urine and blood samples were collected after the exercise protocol. Nitric oxide synthase activity and protein expression and endothelial (e) NOS phosphorylation in the kidney were examined. Exercise training significantly lowered SBP, decreased urinary albumin excretion, thiobarbituric acid-reactive substances levels and renal NADPH oxidase activity, and increased creatinine clearance in SHR. Exercise training significantly increased plasma and urinary nitrate/nitrite, NOS activity and eNOS and neuronal NOS expression, but decreased eNOS phosphorylation at Ser¹¹⁷⁷ and Thr⁴⁹⁵ in kidneys of SHR and WKY rats. Renal NOS may be involved in the antihypertensive and renal protective effects of exercise training in SHR.