Physical training increases renal injury in rats with chronic NOS inhibition

Nitric oxide (NO) is involved in regulation of vascular tone and renal hemodynamics. Inhibition of NO synthase (NOS) by Nomega-nitro-L-arginine methyl ester (L-NAME) promotes systemic hypertension and glomerular damage. Exercise is effective in reducing elevated blood pressure in hypertensive individuals and rats treated with L-NAME. We investigated the effects of regular aerobic exercise on renal injury in hypertensive rats with NOS inhibition. Adult Wistar rats were divided into four groups: sedentary or exercising, nonhypertensive (two groups) and hypertensive, sedentary or exercising (two groups). Treadmill running exercise was prolonged for 4 weeks (60 min.day(-1), 5 days/week, 20 m.min(-1), no incline), and hypertension was induced by L-NAME given orally to rats for 4 weeks (25 mg.kg(-1).day(-1) in drinking water). Blood pressure was monitored at baseline and then once a week throughout L-NAME administration. Kidney sections were examined for renal histopathology. Hypertensive animals exhibited elevated blood pressure, and exercise partly prevented this elevation. Renal injury observed as arteriolar wall thickening, focal tubular atrophy, and interstitial inflammatory infiltration was apparent in hypertensive animals, and exercise induced further renal damage in hypertensive animals. The present training protocol exacerbates renal insufficiency in NOS-blockage hypertension in rats.