Electron microscopy description of cardiomyocytes from the left ventricle of rat heart after apoptosis induction by isoproterenol

Changes in cardiomyocytes from the left ventricle of rat heart were studied by light and electron microscopic and morphometric methods in the myocardial regions neighboring necrotic foci formed after the injection of 80 mg/kg β adrenomimetic isoproterenol. TUNEL assay was used to detect apoptotic cardiomyocytes. Three types of cardiomyocytes (A, B, and C) differing by the ultrastructure of the nucleus and the degree of mitochondrial changes were identified at all studied stages of necrotic focus development (4–48 h). B and C type cardiomyocytes could represent cells at different stages of apoptosis. The apoptotic changes in cardiomyocytes proved to prevail in early lesion foci (4–18 h), while cardiomyocytes at later stages were prone to necrosis; cardiomyocytes can exhibit signs of apoptosis and necrosis at the same time.