The effect of dietary lipids on rat liver mithocondrial swelling

RESUMO

The swelling of liver mitochondria resulting from changes in the dietary fatty acid (FA) was investigated in rats fed two lipid diets for two or four months. Female Sprague-Dawley rats were fed two semi-synthetic and isocaloric diets. One diet (CO diet) contained 10 per cent coconut fat (rich in saturated fatty acids, SFA) while the other (SO diet) contained 10 per cent sunflower seed oil (rich in unsaturated fatty acids, UFA). The initial velocity (Vo) was used to determine the velocity of the spontaneous and phosphate - or calcium-induced sweeling of rat liver mitochondria. The changes in the fatty acid composition of the mitochondrial membranes were expressed as the unsaturation index, as well as the total content of saturated and unsaturated fatty acids and their ratios. The liver mitochondrial phospholipid fatty acid composition was very similar in both diet groups, in spite of the differences in dietary lipid fatty acid content. Only the 160, 161 (@-7) and 161 (@-9) fatty acids of the liver mitochondrial phospholipids differed significantly during the experiment. In general, the diets and the lenght of treatment had no significant influence on the extent of swelling. However, for animals fed the SO diet, significant differences in the for Vo of the phosphate - and calcium-induced swelling was observed. This result probably reflects greater fluidity of the mitochondrial membrane due to the high content of the fatty acid residues which would produce a more flexible and less stable membrane system