Candesartan prevents the progression of glomerulosclerosis in genetic hypertensive rats

The renin-angiotensin system (RAS) has been implicated in the development of hypertensive glomerulosclerosis. However, there are no experimental findings clearly demonstrating activation of glomerular RAS in hypertensive nephropathy. Using the stroke-prone spontaneously hypertensive rat (SHRSP) as an animal model of hypertensive glomerulosclerosis, we examined the relationship between the sequential changes in urinary albumin excretion (UAE), renal morphology, and glomerular mRNA expression for transforming growth factor-beta (TGF-beta) and fibronectin (FN) and glomerular mRNA levels for RAS components, and determined the effects of the angiotensin II (Ang II) type 1 (AT-1) receptor antagonist (candesartan) and equihypotensive hydralazine on these parameters. In SHRSP, UAE was normal at nine weeks of age and increased by 12 weeks. Plasma renin activity, plasma Ang II concentration, and angiotensin converting enzyme (ACE) activity were not higher in 9- and 12-week-old SHRSP than in WKY. RNase protection assay revealed higher glomerular mRNA levels for angiotensinogen, ACE, and AT-1a and AT-1b receptors in 9-, 12-, and 14-week-old SHRSP than in WKY. The glomerular mRNA levels for TGF-beta and FN in SHRSP were increased from nine weeks of age. SHRSP had a greater glomerulosclerosis index (GSI) at 24 weeks of age than did WKY. Administration of candesartan for two weeks, but not of hydralazine, markedly reduced UAE and normalized mRNA levels for TGF-beta, FN, and RAS components. Candesartan administration for 12 weeks virtually prevented the progression of glomerulosclerosis in rats. We conclude that in SHRSP, RAS activation and increased sensitivity to Ang II in glomeruli play important roles in the progression of glomerulosclerosis.