Benidipine inhibits expression of ET-1 and TGF-β1 in Dahl salt-sensitive hypertensive rats

Endothelin and growth factors such as transforming growth factor(TGF)-beta1 are important regulators of the cardiovascular system. Although increased production of endotfielin-1 (ET-1) and TGF-beta1 have been reported in left ventricular hypertrophy, the detailed roles of these substances in hypertrophy remain to be determined. To elucidate the cardioprotective effects of calcium antagonists in left ventricular hypertrophy, we evaluated the effects of long-term treatment with benidipine, a long-acting calcium antagonist, on preproET-1, ETA receptor (ETAR) and TGF-beta1 expression in the left ventricle and evaluated the relations between these effects and myocardial remodeling in Dahl salt-sensitive hypertensive (DS) rats fed a high-salt diet. After 5 weeks of feeding an 8% NaCl diet to 6-week-old DS rats (i.e., at 11 weeks of age), a distinct stage of concentric left Ventricular hypertrophy (DSLVH) was noted. Benidipine (DSLVH-B group, n=8; 1 mg/kg/day, subdepressor dose) or vehicle (DSLVH-V group, n=8) was administered to 6-week-old DS rats for 5 weeks, or until the onset of DSLVH stage, and age-matched (11-week-old) Dahl salt-resistant rats fed the same diet served as a control group (DR-C, n=8). Blood pressure was similar between the DSLVH-B and DSLVH-V groups, but was significantly lower in DR-C rats. The preproET-1, ETAR and TGF-beta1 expressions in the left ventricle were significantly higher in DSLVH-V than in DR-C rats, end significantly lower in DSLVH-B than in DSLVH-V, Benidipine administration resulted in significant improvements in the wall-to-lumen ratio and perivascular fibrosis in the coronary arterioles, and in myocardial fibrosis. We therefore concluded that myocardial remodeling and left ventricular hypertrophy in DS hypertensive rats fed a high-salt diet were significantly ameliorated by a subdepressor dose of benidipine, and that this amelioration was partly due to decreases in the expression of ET-1 and TGF-beta1 in the left ventricle.