Direct comparison of the effects of valsartan and amlodipine on renal hemodynamics in human essential hypertension

Abstract Background To elucidate the renoprotective mechanism of AT1-receptor blockers, we compared the effects of the AT1-receptor blocker valsartan with those of the calcium channel blocker amlodipine on renal hemodynamics and microcirculation. Methods A total of 58 patients (50.2 ± 9.0 years) with mild to moderate essential hypertension were included in a randomized, double-blind study to receive either valsartan (80 to 160 mg) or amlodipine (5 to 10 mg). Renal plasma flow (RPF) and glomerular filtration rate (GFR) were measured before and after 8 weeks of treatment. Glomerular hydrostatic pressure (PGlo) and resistances of the afferent (RA) and efferent (RE) arterioles were calculated according to the Gomez formulas. Results Blood pressure control was similar in both groups. RPF did not change with either treatment. In contrast, GFR increased with amlodipine (+8 ± 14 mL/min; P< .01) but was preserved with valsartan. Amlodipine caused a more marked increase in the RE/RA ratio than valsartan (+0.26 ± 0.26 v +0.13 ± 0.24, P< .05), which was paralleled by an increase in PGlo in patients treated with amlodipine (+1.9 ± 4.3 mm Hg; P< .05) but not in those treated with valsartan. Conclusions At similar blood pressure control, valsartan maintained GFR and PGlo, whereas amlodipine led to glomerular hyperfiltration and an increase in PGlo. The results might explain the favorable renal outcome with AT1-receptor blocker therapy.