Effects of starvation on the carnitine palmitoyltransferase of hepatic peroxisomes.

I t is generally accepted that the mitochondria1 carnitine palmitoyltransferases play an important role in the regulation of hepatic fatty acid oxidation [ I ] . These two enzymes express their activities on either side of the mitochondrial inner membrane that acts as a barrier to the transfer of fatty acids into the mitochondrial matrix. The enzyme that lies outsidc this barrier is located on the mitochondrial outer membrane 121 and can be inhibited by physiological concentrations o f malonyl-CoA 131. An important aspect of the regulation o f the outer carnitine palmitoyltransferase is the change that occurs in its sensitivity t o inhibition by malonylCoA in different physiological and pathophysiological states. Thus, starvation 14-51 and diabetes [ 6 ] both cause a decrease in sensitivity t o inhibition by malonyl-CoA. It has been reported that a carnitine palmitoyltransferase activity is associated with isolated hepatic peroxisomes [ 71 and more recently it has been shown that this carnitine palmitoyltransferase activity can be inhibited by malonyl-CoA [8]. The purpose of this study was t o see how the activity and sensitivity to inhibition by malonyl-CoA of the carnitine palmitoyltransferase activity associated with isolated peroxisomes would be affected by starvation.