Angiotensin II and calcium blockers prevent glomerular phenotypic changes in remnant kidney model

Recent studies on various models of glomerular diseases indicate that glomerular injury is associated with the phenotypic modulation of glomerular cells. However, the effect of renoprotective agents on glomerular phenotype remains to be determined. This study examined the effects of angiotensin II Type 1 (AT1) receptor antagonists and calcium antagonists on glomerular phenotypic changes in rats with subtotal renal ablation. Rats were subjected to 5/6 nephrectomy and were given oral TCV-116, a selective AT1 receptor antagonist (1 mg/kg), manidipine, a dihydropyridine calcium antagonist (3 mg/kg), or vehicle for 8 wk. Glomerular phenotypic modulation was determined by the staining of alpha-smooth muscle actin and desmin in glomerular cells with an immunohistochemical technique. At the start of drug treatment, alpha-smooth muscle actin and desmin were already significantly expressed in the glomerular cells of 5/6-nephrectomized rats, in contrast to a negligible glomerular expression of these proteins in sham-operated rats. Treatment of 5/6-nephrectomized rats with TCV-116 or manidipine significantly decreased glomerular expression of alpha-smooth muscle actin and desmin, thereby indicating that these drugs prevented glomerular phenotypic changes in 5/6-nephrectomized rats. Furthermore, their inhibitory effects on glomerular phenotypic modulation were associated with the prevention of glomerular cell proliferation, hypertrophy, and sclerosis. Therefore, this study provides the first evidence that the renoprotection is linked to the prevention of glomerular phenotypic modulation and supports the idea that this phenotypic modulation may serve as an important cellular marker of glomerular injury.