Ultrastructure of rabbit myocardium in the late period of immobilization stress.

Ultrastructure of working myocardium was studied in rabbits subjected to 70-day immobilization in narrow cages excluding active movements. The structure of working cardiomyocytes, nervous apparatus, and microvascular bed in auricles were studied. Particular attention was focused on intercalated disks in muscle fibers, where separation of fasciae adherents was observed, while desmosomes in the lateral area of these contacts were preserved. The role of these findings in triggering of discoordinated contractions of rabbit auricular cardiomyocytes is discussed.