Histochemical, ultrastructural and cytochemical study of reperfusion effect on ischemic myocardial injury.

We assessed the histochemical, ultrastructural and cytochemical effects of reperfusion on ischemic myocardial cells during the early and late reperfusion phases in two groups of dogs. Group A were 8 dogs undergoing 1 hour occlusion of LAD, and Group B were 14 dogs undergoing 1 hour occlusion of LAD followed by 2 hour reperfusion period. The results of the histochemical study (PAS stain) demonstrated that in Group A, a patchy distribution of glycogen occurred primarily in the subepicardial region. Three-dimensional analysis of this distribution revealed peninsulas of glycogen running parallel with a vessel. The cells in Group B, mainly subepicardium, showed a moderate glycogen content which was more extensive than those in Group A. The ultrastructural changes were assessed after a 60-minute ischemia and subsequent recovery (after 5 minutes and 120 minutes of reflow) using transmural biopsy specimens. Each myocardial cell was graded from 0-4 according to the degree of ischemic injury and recovery. The degree of ischemic damage varied in intensity from slight to severe, in both the subepicardium and the subendocardium. Ca++-ATPase activity was examined cytochemically in myocardial cells of Group B. After 60-minute occlusion, the moderately ischemic cells (especially in the subepicardium) that were without amorphous dense bodies or marked sarcolemmal lifting-off made significantly greater ultrastructural recovery (p less than 0.05) with restoration of Ca++-ATPase activity on sarcoplasmic reticulum and mitochondria after 120 minutes of reflow. This occurred even though after 5 minutes of reflow the cell showed temporary deterioration such as contraction bands, vacuoles and severe destruction of some mitochondria.