Effect of duration of ischemia on myocardial proteome in ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a serious problem resulting from clinical setting of coronary revascularization. Despite extensive studies on I/R injury, the molecular bases of cardiac dysfunction caused by I/R are still unknown, but are likely to result from alterations in protein expression. Isolated rat hearts were subjected to 15-30 min of no-flow ischemia without (Ischemia protocol) or with 30 min of reperfusion (I/R protocol). 2-DE analysis of heart proteins from both experimental protocols showed wide-ranging changes in protein levels. In the Ischemia protocol, 39 protein spots were changed in ischemic groups and those changes correlated with duration of ischemia. Ninety percent of the affected proteins were increased. In contrast to increased protein levels, the total messenger RNA (mRNA) level decreased approximately two fold. Compared to the Ischemia protocol, changes in protein levels in the I/R protocol did not correlate with the duration of ischemia and the degree of recovery of mechanical function. The decrease of affected protein from I/R protocol was associated with the increase in total protein level in reperfusate. Our studies show that the protein increase is correlated with the mechanical function of the I/R hearts and the increase is not likely associated with an increase in protein synthesis.