This proposal is designed to definitively assess the role of NF-kappaB in cardiac ischemia/reperfusion injury (I/R) and late ischemic preconditioning (IPC). Although NF-kappaB activation is associated with I/R, the role of NF-kappaB in myocardial injury remains controversial. We hypothesize that blockade of NF-kappaB activation in I/R has a protective effect against MI. We will test this hypothesis by blocking NF-kappaB chronically using a dominant negative transgenic approach, and acutely by specifically blocking interaction between NF-kappaB and promoter sequence with a decoy oligodeoxynucleotide (ODN). Cardiac IPC, including early and late IPC, is the phenomenon in which brief repetitive episodes of ischemia induce a protective state against a later more serious ischemic insult. There is evidence that transcriptional regulation is critical for the protection afforded by late IPC. Specifically, NF-kappaB is thought to play a major role as a signaling molecule for the induction of protective genes such as iNOS, COX-2, and aldose reductase. We will employ a multidisciplinary approach to identify the role of NF-kappaB in late IPC.