We have previously shown, using Affymetrix gene chip technology, that urocortin induces the expression of several diverse genes in cardiac myocytes. An ATP sensitive inwardly rectifying potassium channel, Katp (Kir6.1), the enzyme calcium independent phospholipase A(2) (iPLA(2)), and protein kinase C epsilon (PKCepsilon) and that these genes are involved in the cardioprotective mechanism of action of urocortin. Here we demonstrate that these gene products are localized to cardiac myocyte mitochondria and for the first time show that urocortin protects cardiac myocytes from ischaemia/reperfusion induced cell death by preventing mitochondrial damage. Using pharmacological agents to Katp channels and iPLA(2) and synthetic peptide inhibitors of PKCepsilon, we go on to demonstrate that these three gene products are involved in the urocortin induced protection of cardiac myocyte mitochondria. These proteins may interact at the mitochondria to produce the protective effect. (C) 2004 Published by Elsevier Inc.