G. Angelos. Degradation of rat cardiac troponin I during ischemia

00149.2004.—Cardiac troponin I (cTnI) degradation has been noted in the stunned myocardium of rodents after ischemia and reperfusion and is one proposed mechanism for the decreased left ventricular (LV) contractility in postischemic hearts. cTnI degradation has been best described after reperfusion of the ischemic myocardium. The effect of ischemia, independent of reperfusion, on cTnI breakdown has not been well characterized. We tested the hypothesis that progressive cTnI degradation occurs with increasing durations of ischemia and that this ischemia-based degradation is, in part, oxidant mediated. Isolated perfused rat hearts underwent global ischemia of 15, 20, or 25 min with and without reperfusion. A second series of hearts was treated with the antioxidants tiron (10 mM) and N-acetylcysteine (4 mM) before 20 min of global ischemia without reperfusion. cTnI degradation was measured using a cTnI-specific antibody and West-ern blot analyses. A progressive increase in cTnI degradation was see