Ezetimibe Improves Endothelial Function and Inhibits Rho-Kinase Activity Associated With Inhibition of Cholesterol Absorption in Humans

Abstract

Ezetimibe is an inhibitor of cholesterol absorption in the intestine. We examined whether ezetimibe improves endothelial function, and if so, what mechanisms are involved. Nineteen healthy subjects (male/female 14/5; mean age, 31±3 [SD] years-old) were randomized to receive ezetimibe (10mg/day) or pravastatin (10mg/day) for 4 weeks in a cross-over manner with a 4-week washout interval. Lipid profiles, flow-mediated dilatation (FMD) and Rho-kinase activity of circulating leukocytes (the extent of phosphorylation of myosin binding subunit, a Rho-kinase substrate) were examined. We also evaluated remnant-like particle cholesterol (RLP-C) known as an up-regulator of Rho-kinase and cholesterol absorption status by measuring cholestanol and campesterol/lathosterol ratio (CLR) (both absorption markers). Although ezetimibe and pravastatin equally reduced low-density lipoprotein cholesterol (E: -25% vs. P: -21%), the CLR was reduced by ezetimibe but was rather increased by pravastatin (E: -41% vs. P: +37%; P<0.01). Reduction in RLP-C by ezetimibe was greater compared with pravastatin (E: -33% vs. P: -14%; P<0.05). Importantly, ezetimibe significantly improved FMD (26%, P<0.05) and reduced Rho-kinase activity (-21%, P<0.05), whereas pravastatin had no such effects. A significant correlation was noted between the reduction in cholestanol and the improvement in FMD (P<0.05). These results indicate that ezetimibe improves endothelial function and inhibits Rho-kinase activity associated with the inhibition of cholesterol absorption, suggesting novel anti-atherogenic effects of the agent in humans.