Effects induced by olive oil-rich diet on erythrocytes membrane lipids and sodium-potassium transports in postmenopausal hypertensive women

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Abstract
Since we have observed that mo-nounsaturated fatty acids (MUFA) enriched diet modifies red cell membrane lipids and cation transport systems in normotensive subjects, we similarly evaluated a group of hypertensive patients undergoing an analogous dietary modification. In a group of 18 moderately hypertensive women, the diet was supplemented for two months with olive oil (about 45 g/day), which replaced an equal amount of seasoning fats. Before and after this period, red cell fatty acid composition was evaluated by gas-chromatography in order to verify diet compliance: a significant increase in oleic acid was observed, while the content of saturated and polyunsaturated fatty acids remained unchanged. After olive oil, maximal rates of Na-K pump (5580±329 vs 6995±390, plt;0.001) and Na-K cotransport ( Na-COT 544±52 vs 877±46, plt;0.001: K-COT 790±76 vs 1176±66, plt;0.001), cell Na content (9.58+0.4 vs 10.61 ±0.6, plt;0.03) and passive permeability for Na (936±74 vs 1836±102, plt;0.001 ) rose significantly. Although the reduction in maximal rate of the Li-Na CT after olive oil was not significant, it was the only cation transport parameter being correlated with the variations of membrane lipids, namely negatively with UFA (r=-0.528, plt;0.05) and positively with SFA (r=0.482, plt;0.005). The change in maximal rate of Li-Na CT was also correlated with the variation of systolic and diastolic BP (r=0.50, plt;0.03). No changes in membrane lipid composition and ion transport systems were observed in a group of 13 control patients kept on usual diet over the same period. Thus, olive oil supplementation affects the lipid composition of the cell membrane in hypertension. This change is in turn associated with a modification of membrane transport activity; in addition a significant reduction of blood pressure is obtained.