Combination therapy with irbesartan and efonidipine for attenuation of proteinuria in Dahl salt-sensitive rats

Abstract

Angiotensin receptor blockers (ARBs) or T- and L-type calcium channel blockers (CCBs) are useful for glomerular protection; however, the protective effects of combination therapy remain unclear. In this study, Dahl salt-sensitive rats were fed a high-salt diet and were treated daily with placebo, irbesartan (60 mg kg-1), efonidipine (30 mg kg -1), irbesartan (60 mg kg-1)efonidipine (30 mg kg -1), amlodipine (3 mg kg-1), or irbesartan (60 mg kg -1)amlodipine (3 mg kg-11) for 4 weeks. Significant reductions in systolic blood pressure were seen in the irbesartan-, efonidipine- and amlodipine-treated groups compared with the placebo-treated group; a further significant reduction was seen in the irbesartanefonidipine-treated group compared with the irbesartan-treated group. Compared with the placebo-treated group, proteinuria was significantly lower in the irbesartan- and efonidipine-treated groups, but not in the amlodipine-treated group. Furthermore, a significant attenuation of proteinuria in the irbesartanefonidipine-treated group compared with the irbesartan-treated group was observed; this effect was not observed in the irbesartanamlodipine-treated group. The glomerulosclerosis index was significantly attenuated by all active treatments except amlodipine. The glomerulosclerosis index in the irbesartanefonidipine-treated group, but not in the irbesartanamlodipine-treated group, was significantly lower than that in the irbesartan-treated group. Significant attenuations of gene expressions of p22 phox, transforming growth factor-β, monocyte chemoattractant protein-1 and collegen I were observed in the irbesartan- and efonidipine-treated groups, but not in the amlodipine-treated group. Values for these parameters were reduced to control levels in the irbesartanefonidipine-treated group. Combination therapy with ARB and T- and L-type CCB might produce a powerful renal protective effect. © 2010 The Japanese Society of Hypertension All rights reserved.