Dysfunction of vascular smooth muscle and vascular remodeling by simvastatin.

Abstract

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, are widely prescribed for hypercholesterolemia. With the increasing use of statins, numerous reports demonstrated that statins can cause damage to skeletal muscles. However, the toxicities of statins on vascular smooth muscle, which are essential to cardiovascular homeostasis, have not been previously described. Here, we examined the effects of simvastatin on the contractile function and the integrity of vascular smooth muscle in isolated rat thoracic aortic rings, primary cultured vascular smooth muscle cells (VSMCs) in vitro and rats in vivo. In aortic rings, simvastatin suppressed the normal agonist-induced contractile responses in time- and concentration-dependent manners (0.86 g ± 0.11 at 10 μM simvastatin for 24 h compared with 1.89 g ± 0.11 at control). The suppression persisted in the endothelium-denuded aortic rings and was irreversible even after wash-out of simvastatin. Simvastatin suppressed the contraction induced by Bay K8644, an activator of voltage-operated Ca²⁺ channel (VOCC) in rat aortic rings and abolished agonist-induced intracellular Ca²⁺ increase in VSMCs. The simvastatin-induced contractile dysfunction was reversed by the supplementation of mevalonate and geranylgeranylpyrophosphate, precursors for protein isoprenylation. Consistently, activation of RhoA, a representative isoprenylated protein, was disrupted by simvastatin in VSMCs and RhoA-mediated phosphorylation of MYPT1 and CPI-17, and tonic tension were also suppressed. Notably, prolonged treatment of simvastatin up to 48 h induced apoptosis of vascular smooth muscle in aortic rings. Most importantly, simvastatin treatment in vivo significantly attenuated the agonist-induced vasoconstriction in rats ex vivo and induced a decrease in luminal area of the vascular wall. Collectively, these results demonstrate that simvastatin can impair the normal vascular contractility by disturbing Ca²⁺ influx and RhoA activity, ultimately leading to apoptosis and structural remodeling.

• Authors: Seojin Kang, Hyang-Hwa Woo, Keunyoung Kim, Kyung-Min Lim, Ji-Yoon Noh, Moo-Yeol Lee, Young Min Bae, Ok-Nam Bae, Jin-Ho Chung
• Journal: Toxicological sciences : an official journal of the Society of Toxicology (Toxicol Sci) Vol. 138 Issue 2 Pg. 446-556 (Apr 2014) ISSN: 1096-0929 [Electronic] United States
• PMID: 24449418 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Hydroxymethylglutaryl-CoA Reductase Inhibitors
• Simvastatin
• Calcium

Topics

• Animals
• Aorta, Thoracic (drug effects, metabolism, pathology, physiopathology)
• Calcium (metabolism)
• Cells, Cultured
• Dose-Response Relationship, Drug
• Hydroxymethylglutaryl-CoA Reductase Inhibitors (toxicity)
• Male
• Muscle Contraction (drug effects)
• Muscle, Smooth, Vascular (drug effects, metabolism, pathology, physiopathology)
• Myocytes, Smooth Muscle (drug effects, metabolism)
• Primary Cell Culture
• Rats
• Rats, Sprague-Dawley
• Simvastatin (toxicity)
• Time Factors
• Vasoconstriction (drug effects)