The influence of linoleic acid intake on membrane‐bound respiratory activities

The fatty acid composition of subcellular membranes, like that of depot fats, can be altered by dietary manipulation. Most attention has been directed toward the effects of feeding an essentialfatty‐acid‐free diet. We chose to examine some responses generated by the feeding of a dietary fat containing a disproportionately high level of an essential fatty acid. Rats were fed diets formulated with beef tallow (BT) to provide 4% (P/S, 0.2) or safflower oil (SO) to provide 24% (P/S, 7.6) of total energy as linoleic acid. Lipids isolated from hepatic mitochondria of rats fed the SO diet contained, in relative terms, 85% more unsaturated bonds. Mitochondria isolated from livers of rats fed either diet were tightly coupled. When all aspects of oxidative metabolism examined in this report are considered, mitochondria of SO group origin exhibited greater oxidative activities but lower ADP/O ratios than did BT mitochondria. Our hypothesis is that the perturbed state of the membrane‐bound phospholipids initiates a remodeling‐response through which an intramitochondria source of ADP is generated to support state‐3 respiratory activity.