[Phospholipid turnover of hepatic subcellular membranes in rats receiving diets with different fat content]

The renewal (turnover) of rat liver mitochondrial an microsomal phospholipids was studied by the pulse-labeled method. As the fat content in the diet was raised (to 9, 26 and 62%), the renewal of mitochondrial phospholipids increased. In the microsomes, the renewal of phospholipids exceeded the control fed both low-fatty and high-fatty diets. The feeding of rats with the low-fatty diet had a substantial effect on the half-life of mitochondrial and microsomal phospholipids, while the half-life of phospholipids labeled in the polar part with 14C-glycerin reduced and that of phospholipids labeled in the fatty acid part by 3H-palmitate considerably rose. It is assumed that under the conditions of inadequate supply of fatty acids with food, the reutilization of fatty acids formed during degradation of membranous phospholipids is activated. As the times of the feeding with experimental diets were raised (up to 60 days), the turnover of membranous phospholipids did not differ significantly from the data obtained in experiments carried out for 30 days. The exception to the rule was the half-life of acyl chains of mitochondrial phospholipids that continued increasing dramatically under 60 days of the low-fatty diet.