ABSTRACT
Dietary alterations were used to demonstrate selective handling of fatty acids during their redistribution in vivo. Differences in the mol per cent of individual acyl chains in the non-esterified fatty acid, acyl-coenzyme A and phospholipid fractions reflected a result of relative precursor abundance combined with enzymic selectivities. Selective distributions were observed in the utilization of individual acyl chains between 16:0 and 18:0, 18:1 and 18:2, and among 20:3, 20:4 and 20:5, 22:6 by ligase(s), hydrolase(s) and acyl-transferases. The variations in the mol per cent of linoleate present in the acyl-coenzyme A fraction of liver relative to that in the non-esterified fatty acids suggested an in vivo regulation of the level of linoleoyl-coenzyme A that influenced the synthesis of both arachidonoyl-coenzyme A and lipids. The greater abundance of eicosapentaenoic acid in the free fatty acid fraction relative to that in the acyl-coenzyme A fraction may increase the ability of dietary 20: 5n-3 to be an effective inhibitor of the synthesis of prostaglandins derived from 20:4n-6.