Combination therapy with an angiotensin-converting enzyme (ACE) inhibitor and a calcium antagonist: Beyond the renoprotective effects of ACE inhibitor monotherapy in a spontaneous hypertensive rat with renal ablation

Abstract

To assess the renal benefits of combined angiotensin-converting enzyme inhibition and calcium antagonism, we studied the antihypertensive and renoprotective effects of temocapril (TMP) alone or in combination with azelnidipine (AZN) in a spontaneously hypertensive rat (SHR) remnant kidney model of chronic renal failure. Male 5/6-nephrectomized SHR/Izumo rats were randomly assigned to receive vehicle (control group), TMP (TMP group; 10 mg.kg-1·day-1), AZN (AZN group; 3 mg·kg-1·day-1), or both (TMP+AZN group) orally for 12 weeks. Systolic blood pressure (SBP) and urinary excretion of albumin (UalbV) were measured every 2 weeks. At the end of the experiment, serum creatinine (Scr), heart weight (HW), and blood urea nitrogen (BUN) levels were measured and the remnant kidneys were examined to determine the index of glomerular sclerosis (IGS). SBP and UalbV in the control group increased progressively throughout the experimental period. TMP, AZN, and TMP+AZN blocked the development of hypertension. TMP+AZN did not enhance the antihypertensive effects of either TMP or AZN used singly. TMP, AZN, and TMP+AZN all significantly decreased the UalbV, Scr, BUN, and HW/body weight (BW) ratio. The level of UalbV and the HW/BW ratio in the TMP+AZN group were significantly lower than those in the TMP and AZN groups, and the level of Scr in the TMP+AZN group was significantly lower than that in the TMP group. TMP, AZN, and TMP+AZN all significantly protected against an increase in the IGS. The IGS in the TMP+AZN group was significantly lower than that in the TMP and AZN groups. These results indicate that both TMP and AZN have antihypertensive and renoprotective effects in this model. They also suggest that simultaneous administration of TMP and AZN provides greater renoprotective effects than TMP alone.