Brief Myocardial Ischemia Produces Cardiac Troponin I Release and Focal Myocyte Apoptosis in the Absence of Pathological Infarction in Swine.

In a porcine model of brief ischemia leading to reversible stunning in the absence of tissue necrosis, we demonstrated delayed release of cTnI that exceeded the 99 percentile for normals 60-minutes after reperfusion and rose to readily detectable levels 24-hours later. While tissue analysis at 60-minutes showed no evidence of infarction, TUNEL staining demonstrated isolated myocytes undergoing apoptosis, which was absent after 24-hours. These results demonstrate that cTnI elevations occur after ischemia of a duration that is insufficient to produce myocyte necrosis and reflect myocyte injury associated with delayed apoptosis in the absence of pathological evidence of infarction.