The effect of decreased plasma cholesterol concentration by atorvastatin treatment on erythrocyte mechanical properties

THE EFFECT OF DECREASED PLASMA CHOLESTEROLCONCENTRATION BY ATORVASTATIN TREATMENT ONERYTHROCYTE MECHANICAL PROPERTIESMehmet UyukluDepartment of Physiology, Akdeniz University Faculty of Medicine, Antalya, Turkey.3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors(statins) are the most commonly used cholesterol-lowering drugs. HMG-CoA is a keyenzyme in the cholesterol biosynthesis pathway and catalyzes the conversion ofHMG-CoA to mevalonate. Increased plasma cholesterol concentration leads tosignificant changes in the structure of membrane lipids and proteins that may impairmembrane function. The recent clinical applications defend the concept to lowerplasma cholesterol levels as much as possible and a lower limit concept has almostdisappeared. It is not clear how very low plasma cholesterol level could affect cellmembrane in general and especially the structure and function of red blood cells(RBC). The aim of this study is to investigate the effect of hypocholesterolemiaresulting from atorvastatin therapy on RBC mebrane structure and mechanicalproperties in guinea pigs fed on a normal diet. Animals were divided into two groups,as ?atorvastatin-treated? (n=12) and control (n=12). Per-oral atorvastatinadministration in isotonic phosphate saline buffer at a dose 20 mg/kg/day has beenplanned once a day for a period of 3 weeks (21 days). The following analyses wereperformed after blood withdrawal via cardiac puncture: plasma total cholesterol,triglyceride (TG), low-density (LDL) and high-density (HDL) lipoproteinconcentrations, erythrocyte deformability, RBC plasma membrane Na+-K+ ATPaseactivity, lipid composition of RBC mebranes. The atorvastatin-treated group exhibitedlower concentrations of cholesterol (17.42 ±1.70 mg/dL), LDL-cholesterol (5.250 ±2.2mg/dL) and TG (42.60± 3.7mg/dL) than the control group ( 34.08 ±1.72, 21.17 ±1.4,60.64 ± 2.4 mg/dL, respectively). The RBC membrane lipids showed significantdifference (P < 0.0001) between the two groups, however there was not anydifference between the groups with respect to the RBC deformability.Key words: cholesterol, atorvastatin, erythrocyte membrane, erythrocytedeformability.