The chronic effect of nitrendipine on heart and regional blood flow in renovascular hypertensive rats.

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Abstract
Nitrendipine, a new calcium entry blocker, was administered to renovascular hypertensive rats (2K1C Goldblatt) (RHR, n = 8) and sham operated control rats (ShC, n = 8) to evaluate the effects on left ventricular hypertrophy and regional blood flow using radioactive microspheres. Nine untreated RHR and 8 untreated ShC served as control groups. After 6 weeks treatment (20 mg/kg subcutaneously, every other day), blood pressure reduced significantly in both RHR and ShC associated with a reduction in total peripheral resistance. Significant reversal of left ventricular hypertrophy was noted in RHR (1278 .+-. 41 to 1024 .+-. 19 mg, p < 0.01), but not in ShC. There was a significant relationship between blood pressure and left ventricular mass in both untreated rats (r = 0.955, p < 0.001) and treated rats (r = 0.729, p < 0.005). Nitrendipine increased coronary blood flow in RHR (430 .+-. 30 to 566 .+-. 47 ml/m/100 g, p < 0.05) as well as in ShC (375 .+-. 15 to 508 .+-. 29 ml/m/100g, p < 0.05), without increasing cardiac oxygen demand. Renal blood flow was unchanged, whereas cerebral blood flow was significantly increased in both RHR (128 .+-. 6 to 164 .+-. 13 ml/m/100g, p < 0.01) and ShC (124 .+-. 7 to 173 .+-. 5 ml/m/100g, p < 0.01). Thus, long treatment of nitrendipine effectively regressed cardiac hypertrophy toward normal. Nitrendipine reduced total peripheral resistance; however, the effects on regional blood flow were not uniform among various organs.