Protective effects of lovastatin on vascular endothelium injured by low density lipoprotein

To examine protective effects of lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, on endothelial dysfunction induced by a single intravenous injection of natural low density lipoprotein (n-LDL) and analyze the possible action mechanism of lovastatin.

Rats were treated by intraperitoneal injection with lovastatin at dose of 2 or 4 mg/kg body weight once daily for 7 d, and on d 6 a single injection of n-LDL 4 mg/kg was given by sublingual vein. Forty eight hours after injection of n-LDL, the descending thoracic aorta of rats was taken. Acetylcholine (ACh)-induced endothelium-dependent relaxation (EDR) and sodium nitroprusside (SNP)-induced endothelium-independent relaxation of aortic rings were examined in vitro. Malondialdehyde (MDA), nitric oxide (NO), and activity of superoxide dismutase (SOD) as well as level of lipid in serum were analyzed.

A single injection of n-LDL inhibited ACh-induced EDR compared with normal control group (maximal relaxation rate: 69.5 %+/-1.2 % vs 91.0 %+/-1.2 %, P<0.05), decreased serum NO level [(7.0+/-0.5) micromol/L vs (11.2+/-0.9) micromol/L, P<0.05] and serum SOD activity [(371+/-16) kNU/L vs (405+/-18) kNU/L, P<0.05] and elevated serum MDA level [(5.4+/-0.5) micromol/L vs (3.0+/-0.8) micromol/L, P<0.05]. Compared with n-LDL treated group, lovastatin 2 and 4 mg/kg increased EDR( maximal relaxation rate 82.9 %+/-0.5% and 83.7 %+/-0.7 % vs 69.5 %+/-1.2 %, P<0.05) and elevated NO level [(11.0+/-0.7) and (11.2+/-0.8) micromol/L vs (7.0+/-0.5) micromol/L, P<0.05], increased SOD activity [(402+/-15) and (408+/-25) kNU/L vs (371+/-16) kNU/L, P<0.05], and reduced serum MDA level [(3.3+/-0.6) and (3.5+/-0.4) micromol/L vs (5.4+/-0.5) micromol/L, P<0.05]. But sodium nitroprusside-induced endothelium-independent relaxation and the level of serum lipid in both saline+LDL group and lovastatin-treated group had no marked alteration.

Lovastatin was able to protect vascular endothelium from dysfunction induced by a single injection of n-LDL.