A morphometric analysis of ischemic canine myocardium with and without reperfusion.

Progressive morphological changes have been quantitated in ischemic and control regions of canine hearts previously assessed biochemically and physiologically. Muscle strips removed after a 5 or 10-min occlusion of the left circumflex artery were compared to those removed after reperfusion for 20 or 60 min following 10 min occlusion and to those removed immediately from normal and sham-operated dogs. Decreased glycogen content and decreased mitochondrial matrix were observed in fibers from ischemic regions as early as 5 min after ligation. Changes in the mitochondrial volume fraction were calculated by the point counting method and changes in the number of lipid droplets per unit area were determined. Mitochondrial volume fractions in ischemic regions were not significantly higher when compared to control regions of the same hearts, and were similar to the values measured for 10 and 70-min sham-operated dogs. We conclude that in early acute ischemia considerable variability in the different control groups emerges with extensive sampling and must be considered in interpreting ultrastructural changes.