Fatty acids incorporation into adipose tissue triglycerides

All changes in fatty acid level, with the exception of llnoleic acid in the LEAR oil group, returned to pretest fat levels (day 10) with a return to the mixed fat diet for 8 days (day 32 to 39). As In other species (Walker, 1972), very little erucic acid was incorporated into serum phospholipids even though erucic acid comprised nearly 40% of the fat on the HEAR oil regimen. Fatty acid analyses of fat biopsies obtained from the middorsal abdomen of two of the subjects on the HEAR oil regimen on days 10 and 32 indicated that very little erucic acid was incorporated into adipose tissue. Erucic acid made up 0.4 and 2.0% of the total fatty acids of the two subjects on day 32. The low levels of erucic acid incorporated into phospholipids and triglycerides suggest that erucic acid is converted to other fatty acids, presumably oleic acid, in man as in other species. 

Not all of the chylomicron triglycerides have to pass through the liver and recycle in the blood as lipoproteins, in order to be incorporated in adipose tissue. A part of the chylomicron triglycerides may be taken up directly. This depends on the nutritional state of the animal. When fatty acid labelled chylomicra are injected into a fasting animal only small amounts can be discovered in adipose tissue, short intervals after the injection. However, if this experiment is performed with a carbohydrate fed animal, as much as 25% can be found in adipose tissue after short periods (Bragdon and Gordon 1958). 

This large input of energy is stored in the synthesized fatty acids and is one of the reasons it is so difficult to lose excess weight due to fat. After synthesis, the fatty acids are incorporated into triglycerides and stored in the form of fat in adipose tissues. 

No significant incorporation of free fatty acid into triglyceride or phospholipid occurred in the unfortified adipose tissue homogenate when ATP or CoA was omitted this finding is in accord with Eq. (5), which indicates that the fatty acid must be activated before it is incorporated into phosphatidic acid. Glycerol could not replace a-glycerophosphate in the system. 

In the fasting state, non-esterified fatty acids can supply 50% or more of the body s energy requirements. They are released from adipose tissue and are carried to other tissues where they are further metabolized to supply energy. If there is an excess of non-esterified fatty acids, they are resynthesized into triglycerides and incorporated into pre-jO-lipoproteins. 

---