DIETARY N-3 FATTY-ACIDS INFLUENCE THE LIPID-COMPOSITION AND PHYSICAL-PROPERTIES OF LIVER MICROSOMAL-MEMBRANES IN DIABETIC RATS

We examined the effect of n-3 fatty acid consumption on the lipid comp osition and physical properties of liver microsomal membranes in norma l and experimental diabetic rats. Lipid analysis showed a significant increase in the cholesterol:phospholipid ratio in membranes of normal animals fed n-3 fatty acids as well as in both groups of diabetic rats . These changes would be in part responsible for the higher fluorescen t polarization of DPH (1,6-diphenyl-1,3,5 hexatriene) observed in the diabetic groups compared with the normal ones. These alterations were partially compensated by an increase in the amount of phosphatidylchol ine in the diabetic rats fed on n-3 fatty acids. However, proteins als o play a role in determining the physical properties of the liver micr osomes because in the liposomes derived from them, the fluorescent pol arization of DPH decreased in the diabetics fed n-3 fatty acids. Measu rements of fluorescence anisotropy of n-AS (2-, 7 and 12(9 anthroyloxy ) stearic acid) probes revealed a restricted rotational mobility in th e middle zone of the bilayer. Consistently with this finding there was an elevation in the calculated unsaturation density of the fatty acid s at the carbon 8 position. These experiments confirm the lipid abnorm alities that take place in experimental diabetes and they show further that n-3 fatty-acid administration causes certain compensatory, and t hus beneficial, changes in these abnormalities.