Simvastatin Acts Synergistically with ACE Inhibitors or Amlodipine to Decrease Oxygen Consumption in Rat Hearts

Abstract

Statin drugs, which are cholesterol-lowering agents, can upregulate endothelial nitric oxide synthase (eNOS) in isolated endothelial cells independent of lipid lowering. We investigated the effect of short-term simvastatin administration on NO-mediated regulation of myocardial oxygen consumption (MV(O2)) in tissue from rat hearts. Male Wistar rats were divided into (a) control group (n = 14), and (b) simvastatin group (n = 10, 20 mg/kg/day by oral gavage). After 2 weeks, left ventricular myocardium was isolated to measure MV(O2) using a Clark-type oxygen electrode, and aortic plasma nitrates and nitrites (NOx) were measured. Baseline plasma NOx levels (19+/-2.6 in control vs. 20+/-2.5 microM/L in simvastatin) and baseline MV(O2) (288+/-23 in control vs. 252+/-11 nmol/g/min; p = 0.09) were not significantly different between the two groups. NO-dependent regulation of MV(O2) in response to bradykinin, ramipril, or amlodipine was augmented in simvastatin rats compared with controls (p < 0.05). Decrease of MV(O2) from baseline in response to highest doses in control versus simvastatin groups was as follows-bradykinin, -28+/-5% vs. -44+/-6%; ramipril, -35+/-5% vs. -50+/-8%; and amlodipine, -32+/-9% vs. -42+/-3%. Response to highest dose of NO donor S-nitroso N-acetyl penicillamine (SNAP) was not significantly different in the two groups (-55+/-5% vs. -52+/-7%). Treatment with Nw-nitro-L-arginine methyl ester, inhibitor of NO synthesis, attenuated the effect of bradykinin, ramipril, and amlodipine on MV(O2) (p < 0.05). In conclusion, short-term administration of simvastatin in rats potentiates the ability of angiotensin-converting enzyme (ACE) inhibitors and amlodipine to cause NO-mediated regulation of MV(O2).