Acclimation to low temperature is associated with an increase in long-chain acyl-CoA synthetase in rainbow trout (Oncorhynchus mykiss) heart

Abstract

Rainbow trout (Oncorhynchus mykiss) were acclimated to 5 and 15 °C. Uptake of radiolabelled palmitate by isolated cardiomyocytes was linear for at least 65 min. Myocytes from fish acclimated to 5 °C and tested at 5 °C showed higher rates of uptake than those from fish acclimated to 15 °C and tested at 5 °C. There was no significant difference in fatty acid uptake between myocytes from fish acclimated to 5 and 15 °C and tested at their respective acclimation temperature. Acclimation temperature had no effect on levels of intracellular fatty acid binding protein or carnitine palmitoyltransferase. However, acclimation to low temperature resulted in a twofold enhancement in fatty acyl-CoA synthetase activity, which increased in a linear fashion over a 28-day period. An increase in fatty acyl-CoA synthetase, which occurs on the outer mitochondrial membrane and the endoplasmic reticulum, is possibly related to low temperature-induced changes in fatty acid oxidation and synthesis of complex lipids.