[State of the contractile apparatus of myocardial cells in ischemic injury].

Micrometric studies of the sarcomeres of myocytes in the zone of experimentally induced myocardial ischaemia in rats, histological, polarization-microscopic and micrometric studies of the myocardial cells in the zone of infarction in dead humans and model experiments with fixation of distended papillary muscles demonstrated that relaxation of the sarcomeres is characteristic of the myocardial cells damaged by ischaemia. This sign indicating the loss of the contractile function in the injured cells develops in early ischaemia when other histological changes typical for the ischaemic lesions are absent. The percentage of relaxed and distended sarcomeres changes with the increasing duration of ischaemia, and therefore it can be used as an indirect index of the term of ischaemia and, consequently, as a criterion of the irreversibility of the ischaemic lesion of the myocardium.