SUMMARY
1. 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.
2. 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.
3. 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.
4. 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.
5. Renal NOS may be involved in the antihypertensive and renal protective effects of exercise training in SHR. Key words: exercise, hypertension, kidney, nitric oxide synthase, spontaneously hypertensive rats.
INTRODUCTION
Numerous epidemiological studies have reported that exercise has regulatory effects on blood pressure.1 In experimental studies, exercise has also been reported to reduce blood pressure in spontaneously hypertensive rats (SHR),2 Dahl salt-sensitive rats3 and angiotensin II-infused rats.4 In addition to its blood pressure regulatory effects, exercise has renal protective effects, including decreasing plasma creatinine and proteinuria and improving glomerular sclerosis, in rats with chronic renal failure (CRF)5,6 or diabetic nephropathy,7 as well as in fructose-fed SHR.8 However, the mechanisms responsible for the beneficial effects of exercise are not fully understood.
