Adaptation of muscle to exercise. Increase in levels of palmityl Coa synthetase, carnitine palmityltransferase, and palmityl Coa dehydrogenase, and in the capacity to oxidize fatty acids.

The capacity of gastrocnemius and quadriceps muscles to oxidize palmitate, oleate, linoleate, palmityl CoA, and palmityl carnitine doubled in rats subjected to a program of treadmill running. The rate of palmitate oxdation by whole homogenates of, or the mitochondrial fraction from, leg muscles was twice as great per gram wet weight of muscle in the trained as in the sedentary animals over a wide range (0.125-1.5 mM) of palmitate concentrations. The levels of activity of carnitine palmityltransferase, palmityl CoA dehydrogenase, and mitochondrial ATP-dependent palmityl CoA synthetase expressed per gram of muscle doubled in gastrocnemius and quadriceps muscles in response to the running program. The protein content of the mitochondrial fraction from these muscles was increased approximately 60%.