Olive oil normalizes the altered distribution of membrane cholesterol and Na +Li + countertransport activity in erythrocyte of hypertensive patients

Abstract

The effects of olive oil (OO)- and high-oleic sunflower oil (HOSO)-enriched diets on erythrocyte membrane cholesterol distribution (by means of cholesterol oxidation after continuous cholesterol oxidase treatment) and Na +Li + countertransport activity in control subjects and patients with untreated essential hypertension (with or without concomitant hypercholesterolemia) have been examined. The participants were 12 normotensive and sixteen hypertensive women who consumed in randomized order the two monosaturated fatty acid (MUFA) diets over 4-week periods separated by a 4-week washout period. The half-times for cholesterol oxidation were significantly higher in hypertensive women, ranging from an increase of 38 to 57% in the normo-(20.6 ± 2.8 min; P < 0.001) and hyper-(23.4 ± 4.2 min; P < 0.001) cholesterolemic groups. There was a general decrease by 75% in the half-time for cholesterol oxidation after HOSO diet. Interestingly, the oxidation rates were almost normalized after OO diet. The activity of Na +Li + countertransport was found to be significantly higher in hypertensive women, ranging the increase from 22 to 57% in the normo-(0.314 ± 0.043 mmol × [h × liter cell] −1; P < 0.01) and hyper-(0.405 ± 0.086 mmol × [h × liter cell] −1; P < 0.01) cholesterolemic groups. This transport system was further activated after HOSO diet, while almost restored after OO diet. These findings suggest that dietary OO, but not HOSO, is helpful for normalizing the impaired distribution of membrane cholesterol and reducing elevated activity of Na +Li + countertransport in erythrocyte of hypertensive patients. This action of OO also indicates that alterations in membrane cholesterol distribution may be relevants for the pathogenesis of hypertension. The effects, however, cannot be exclusively attributed to the content of MUFAs (mainly oleic acid) in the diet, as HOSO was unable to induce favorable changes.