HUMAN ERYTHROCYTE-MEMBRANE FLUIDITY AND INSULIN BINDING ARE INDEPENDENT OF DIETARY TRANS-FATTY-ACIDS

Substitution of selected saturated fatty acids of the diet of 29 men a nd 29 women with cis or trans monounsaturated fatty acids did not affe ct erythrocyte membrane fluidity, insulin binding, and the membrane ch olesterol and phospholipid concentrations. Subjects were fed four diff erent controlled diets with a total fatty acid content of 39 to 40 ene rgy percent for four 6-week periods in a Latin square design. The diet s were: (I) high oleic acid (16.7 energy percent oleic); (2) moderate trans (3.8 energy percent trans fatty acids); (3) high trans (6.6 ener gy percent trans fatty acids); and saturated (16.2 energy percent laur ic + myristic + palmitic acids). There were no significant diet effect s on red cell ghost fluidity determined by fluorescence polarization o f the hydrocarbon probe 1, 6-diphenyl-1,3,5-hexatriene (DPH) and the p olar analog trimethylammnonium-DPH (TMA-DPH). There were limited died effects on fluidity of membranes as determined with DPH-propionic acid (DPH-PA) for the men. Insulin binding was more closely associated wit h anisotropy of fluorescence of the surface probe, DPH-PA, than with t hat of the other probes, which is compatible with the localization of the insulin receptor in a domain at the cell membrane surface.