Acclimation to cold and activity of apoptosis in rat myocardium

Abstract

“Price” of an organism acclimation to cold is reducing specific functions of organs and systems. We studied the hormonal and metabolic changes in blood and myocardium of male Wistar rats during adaptation to cold (+4C) within 35 days. It was established that the 10-th day of acclimation are critical, the body temperature drops to more than 1.5C, at this time there was a maximum lethality of animals. At the same time there was a significant reduction in peak systolic pressure. We revealed changes in the production of hormones with 2–3 fold increase in the blood content of corticosterone, adrenaline and thyroxine. We established significant decrease in transmembrane potential of leukocytes on the 10-th day of study with a gradual recovery by the end of the experiment. We showed an increase concentration of TNF, content of DNA fragments and caspase-3 and -8 activities on 35–50% in homogenates of heart on the 10-th day of the experiment. Decrease in body temperature correlated with the accumulation of DNA fragments and caspase-3 in the myocardium (p = 0.68 and 0.74, respectively). Thus, our results indicate that on the background of hormonal rearrangement in the dynamics of cold exposure there is activation of apoptosis in the myocardium, which may contribute to myocardial dysfunction and failure of the adaptation process.