EFFECTS OF COLD ACCLIMATION ON THE ACTIVITY LEVELS OF CREATINE KINASE, LACTATE DEHYDROGENASE AND LACTATE DEHYDROGENASE ISOENZYMES IN VARIOUS TISSUES OF THE RAT

The effects of cold acclimation on the activity levels of creatine kinase, lactate dehydrogenase and lactate dehydrogenase isoenzymes in various tissues/ organs of the rat ( Rattus norvegicus ) were investigated. Male Sprague‐Dawley rats were divided into two groups. One group was housed at 4±1°C (experimental group) and the other at 24±1°C (control group) for six months. The rats were housed in single cages and had access to food and water ad libitum. The tissues/organs investigated were heart, liver, lung, kidney, gastrocnemius muscle and interscapular brown adipose tissue as well as serum. With the exception of lung, (which showed a decrease of 24%) total creatine kinase activity levels were significantly increased ( P< 0.05) in all the tissues/organs investigated (17–51%) as well as serum (34%), in cold acclimated animals. Cold acclimation also resulted in significantly increased ( P< 0.05) activity levels of lactate dehydrogenase in all the tissues/organs investigated (14–24%) as well as serum (35%). Cold exposure resulted in an increase of the activity levels of all the detectable isoenzymes of lactate dehydrogenase, although not always significant, in all the tissues/organs investigated as well as serum. The M 4 tetramer of lactate dehydrogenase was the only detectable isoenzyme in serum.