[Effects of nisoldipine in heminephrectomized spontaneously hypertensive rats--measurement of afferent and efferent arterioles by microvascular cast].

In this study, we measured cross sectional areas of glomerular arterioles and glomerular volume in heminephrectomized spontaneously hypertensive rats (SHR) treated with a calcium antagonist, nisoldipine (NSL). We also examined the relevance of these parameters to the progression of hypertensive renal injury. Male 6-week-old SHR (n = 14) were heminephrectomized and divided into 2 groups. They were fed regular chow (control, n = 7) or chow containing 0.1% NSL (n = 7). After 12 weeks, urinary protein excretion (UpV) and systolic blood pressure (SBP) were measured. The control rats developed marked hypertension reaching 228 +/- 2 mmHg, and NSL lowered this by 27 mmHg (p < 0.001). NSL reduced UpV by 22% (p < 0.05). Microvascular cast of the kidney was prepared, and the cross sectional areas of the afferent and efferent arterioles as well as glomerular volume were measured using scanning electron microscopy. In the juxtamedullary and subcapsular glomeruli with minor abnormalities, the afferent arteriole was narrower and the glomerular volume was smaller in the NSL-treated rats than in the control rats. These results suggest that the calcium antagonist, NSL, offers the advantage of protecting kidney from hypertensive injury by reducing afferent arteriolar diameter, glomerular hypertrophy and intraglomerular pressure in heminephrectomized SHR.