A comparison of the influence of diets high in saturated versus unsaturated fatty acids on lipid composition and glucose-6-phosphatase activity of rat liver microsomes.

Glucose-6-phosphatase (G6Pase) activity in microsomes (M-SF) prepared from livers of rats fed a saturated fat-enriched diet has been observed to be 20-30% higher than in microsomes (M-PUF) prepared from rats fed a polyunsaturated fat-enriched diet. This difference was persisted throughout the 49 days experimental period. Neutral lipids of M-PUF contained a significantly higher concentration of 18:2 and 20:4, and a lower concentration of 16:0, 18:0 and 18:1 whereas in phospholipids 18:2 and 20:4 accumulated at the expense of 16:0 as compared to M-SF. Total phospholipid content from M-PUF was 30% lower than that from M-SF but the proportional phospholipid composition remained the same. An increase in cholesterol content was observed in M-PUF and this increase was localized in the ester fraction of cholesterol. These observations clearly indicate that manipulations of dietary lipids can influence both the fatty acid profiles and enzyme function of hepatic microsomal membranes.