OLIVE OIL NORMALIZES THE ALTERED DISTRIBUTION OF MEMBRANE CHOLESTEROLAND NA-LI+ COUNTERTRANSPORT ACTIVITY IN ERYTHROCYTE OF HYPERTENSIVE PATIENTS()

The effects of olive oil (OO)- and high-oleic sunflower oil (HOSO)-enr iched diets on erythrocyte membrane cholesterol distribution (by means of cholesterol oxidation after continuous cholesterol oxidase treatme nt) and Na+-Li+ countertransport activity in control subjects and pati ents with untreated essential hypertension (with or without concomitan t hypercholesterolemia) have been examined. The participants were 12 n ormotensive and sixteen hypertensive women who consumed in randomized order the two monosaturated fatty acid (MUFA) diets over 4-week period s separated by a 4-week washout period. The half-times for cholesterol oxidation were significantly higher in hypertensive women, ranging fr om 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. The re was a general decrease by 75% in the half-time for cholesterol oxid ation 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 i ncrease from 22 to 57% in the normo- (0.314 +/- 0.043 mmol x [h x lite r cell](-1); P < 0.01) and hyper (0.405 +/- 0.086 mmol x [h x liter ce ll](-1); P < 0.01) cholesterolemic groups. This transport system was f urther 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 redu cing elevated activity of Na+-Li+ counter-transport in erythrocyte of hypertensive patients. This action of OO also indicates that alteratio ns in membrane cholesterol distribution may be relevants for the patho genesis of hypertension The effects, however, cannot be exclusively at tributed to the content of MUFAs (mainly oleic acid) in the diet, as H OSO was unable to induce favorable changes. (C) Elsevier Science Inc. 1997.