Essential fatty acids and ionic permeability of lecithin membranes

Abstract

Lecithins were isolated from egg yolk, and from internal organs of fish, essential fatty acid (EFA)-deficient rats, and control rats. From each, lecithin-dicetyl phosphate liquid-crystal vesicular particles were formed in 145mM NaCl. Extraparticulate Na + was removed by dialysis, and the subsequent rate of Na + efflux from within the particles was determined at various temperatures. The “membranes” of EFA-deficient lecithin permitted a faster rate of Na + efflux at 25°C and a slower rate at 50°C than those of egg, fish, or control rat lecithins. At 37°C the rate of Na + efflux from within “membranes” of EFA-deficient rat lecithins was greater than that for the “membranes” of control rat lecithins. Activation energies for Na + efflux, as calculated from Arrhenius Plots, were 15, 11.5, 9.5, and 4.5 kcal/mole Na + for control rat, fish, egg, and EFA-deficient rat lecithin “membranes,” respectively. The percentages of linoleic (ω6) and linolenic (ω3) fatty acid families, respectively, were: control rat-43.6% and 2.3%; fish-15.5% and 39.1%; egg-30.2% and 0.6%; and EFA-deficient rat-4.5% and 1.0%. Differences in ω6 and ω3 fatty acid levels appeared to be more closely related to differences in activation energies than were differences in individual fatty acid levels.