[Renal hemodynamics and development of renal fibrotic lesions during hypertension]

Hypertension is frequently associated with the development of renal fibrosis leading to chronic renal failure. The objective of the present study was to evaluate the role of blood pressure and renal hemodynamics on the development of renal lesions during hypertension. To this end, rats were treated with a NO synthase inhibitor, L-NAME, for 4 weeks. At this time point, systolic blood pressure reached 170 mmHg, renal blood flow dropped to 3.3 +/- 0.7 ml/min and kidneys displayed glomerular and tubulo-interstitial lesions as evidenced by histological analysis. Thereafter, L-NAME treatment was combined with an AT1 receptor antagonist, losartan (30 mg/kg/d), for an additional period of 4 weeks. Treatment with losartan for 4 additional weeks did not significantly modify hypertension (168 mmHg) either the degree of tubulo-interstitial lesions; in contrast, a significant regression of ischemic and sclerotic glomerular lesions was observed. In parallel, renal blood flow was significantly improved by losartan (5.2 +/- 0.8 ml/min). In addition a negative correlation was observed between renal blood flow and index of glomerulosclerosis (r = -0.82), whereas tubulo-intarstitial damage was positively correlated to systemic pressure (r = 0.93). In conclusion, inhibition of the local effects of angiotensin II alleviates the fall of renal blood flow consecutive to NO deficiency and reduces the morphological and functional lesions of glomeruli, independently of the changes in blood pressure. In contrast, tubulo-interstitial lesions are not correlated with the levels of renal blood flow and do not regress with the blockade of AT1 receptors when rats remain hypertensive.