Possible mechanism of the reorganization of the cardiomyocyte plasma membrane in the suslik in the hibernation-arousal-wakefulness cycle

Studies have been made on the ultrastructure of cardiomyocytes during hibernation and arousal of the ground squirrel C. undulatus. It was found that the number of elements of the rough endoplasmic reticulum, Golgi complex, vesicles and ribosomes increases in the perinuclear areas of cardiomyocytes during arousal of animals. These areas are saturated with lipid inclusions and mitochondria. Numerous vesicles and fringed bubbles were found near the plasma membrane which has many caveolae. These findings may indicate the intense metabolism of the membrane material between plasmalemma and cytoplasmic vesicles. Possible mode of rapid reorganization of the sarcolemma and changes in its functional properties during hibernation-arousal stages are suggested. It is concluded that apart from structural and functional properties which are acquired by cells during preparation of animals to hibernation and which exhibit only small changes during the whole period of hibernation, cyclic changes in plasmalemma structure and function occur during arousal of the ground squirrels.