Cardiorenal Protective Effects of Year-Long Antihypertensive Therapy With a Angiotensin-Converting Enzyme Inhibitor or a Calcium Channel Blocker in Spontaneously Hypertensive Rats

Background The objective of this study was to evaluate the effect of year-long antihypertensive therapy with a calcium channel blocker and an angiotensin-converting enzyme (ACE) inhibitor on cardiac and renal injury. Methods Male 15-week-old spontaneously hypertensive rats (SHR) were given either a normal diet and normal drinking water (n = 10), a diet containing 0.05% nitrendipine (n = 10), or drinking water containing 50 mg/L of quinapril (n = 10). After 12 months of antihypertensive treatment, cardiovascular organ injuries were evaluated. Results Tail–cuff blood pressure (BP) at 12 months was significantly lower in animals receiving nitrendipine or quinapril than in control animals (control, 231 ± 2 mm Hg; nitrendipine, 194 ± 3 mm Hg; quinapril, 191 ± 3 mm Hg; P< .001). Furthermore, aortic thickness was reduced by nitrendipine (−19%, P< .001) or quinapril (−21%, P< .001), and cardiac ventricular weight was significantly reduced by quinapril (−18%, P< .001) but not by nitrendipine (−5%, P = not significant [NS]). Echocardiography at 12 months revealed that midwall fractional shortening was higher in the quinapril group than in the control or the nitrendipine groups (control, 9.3% ± 0.5%; nitrendipine, 9.8% ± 0.5%; quinapril, 10.6% ± 0.6%; P< .05). Left ventricular hydroxyproline levels were lower in the nitrendipine group (−21%, P< .01) and the quinapril group (−36%, P< .001) than in the control animals. In control SHR, creatinine clearance began to decrease and proteinuria began to increase at 6 to 9 months. Quinapril but not nitrendipine attenuated these markers of renal impairment (creatinine clearance at 12 months: control, 4.7 ± 0.4 mL/min/kg; nitrendipine, 5.0 ± 0.4 mL/min/kg; quinapril, 6.1 ± 0.4 mL/min/kg; P< .05). Histologically, the glomerular injury score was lower in the quinapril group than in the control or nitrendipine groups (control, 19 [range, 8 to 30]; nitrendipine, 18 [range, 9 to 32]; quinapril, 7 [range, 3 to 12]; P< .01). Conclusions It is suggested that year-long antihypertensive therapy with an angiotensin-converting enzyme (ACE) inhibitor is superior to a calcium channel blocker in terms of cardiorenal protection in SHR.