| Abstract: | Myocardial ischemia was produced in 12 dogs by ligation of the anterior descending branch of the left coronary artery. The animals were sacrificed 0.5, 1, 3, 6, 12, and 24 hours later. The ischemic area was compared with control tissue from the posterior aspect of the left ventricle as to the glycogen content, myoglobin content, intracellular diffusion of IgG, diastase resistant-periodic acid-Schiff (PAS) (D-PAS) staining material and basic fuchsin-staining material. In the earliest time period studied, 0.5 hours, glycogen loss marked a large area of ischemic change. Myoglobin loss, intracellular diffusion of IgG, D-PAS-staining material and basic fuchsin-staining material were also found but involved only a small area within the glycogen-depleted zone. As the length of ischemic period increased, the area occupied by these changes approached the size of the area of glycogen loss. In all animals, the area of myoglobin loss, intracellular diffusion of IgG, D-PAS staining and basic fuchsin staining were in the area of glycogen loss. The IgG, D-PAS, and basic fuchsin parameters, in turn, were within the area of myoglobin loss but usually did not completely fill it. That is, some fibers showing myoglobin loss did not show the other changes. Can any of these changes serve as early markers for irreversible ischemic injury? Glycogen loss clearly does not. Additional data are needed to determine whether the extracellular diffusion of myoglobin and the intracellular diffusion of IgG are markers of irreversible injury. |
