Effects of HMG-CoA reductase inhibition by simvastatin on vascular dysfunction induced by lipopolysaccharide in rats

Aims: Statins have been identified as a potentially interesting treatment against sepsis. Here, we study the vascular reactivity of aortae from rats treated with lipopolysaccharide (LPS), 4 mg (.) kg(-1), following chronic administration of simvastatin (SV) 10 mg (.) kg(-1). Methods: The rats were treated with either vehicle or SV for 4 weeks before administration of LPS. After 18 h, the systolic blood pressure (SBP) was measured using a tail cuff and vascular and endothelial responses of aortic rings to several agonists were studied in an organ bath. Results: LPS injection decreased the SBP by 38 mm Hg and vascular response to phenylephrine (Phe) by 60%. Plasma nitrates and nitrites (NOx) were 3-fold higher after LPS. This attenuated response to Phe was prevented by incubation with either the inducible-nitric-oxide-synthase (iNOS)selective inhibitor 1400W or the endothelial nitric oxide synthase (eNOS)/iNOS nonselective blocker L-NAME. The presence of endothelium did not alter these findings. Administering LPS to SV-treated rats also decreased the SBP and increased the NOx concentration. The impaired response to Phe was restored by blocking NO synthesis in endothelium-denuded but not in intact aortic rings. The response to acetylcholine demonstrated an enhanced reduction in arteries from the SV + LPS group compared with the LPS group. The inhibition of iNOS prevented acetylcholine-induced relaxation in rings from LPS-treated rats but not in those from the SV + LPS group. Conclusion: These results suggest that statins may reduce iNOS-mediated NO production in endothelial but not in vascular smooth-muscle cells. Copyright (C) 2008 S. Karger AG, Basel.