Reactive oxygen species precede protein kinase C-δ activation independent of adenosine triphosphate-sensitive mitochondrial channel opening in sevoflurane-induced cardioprotection

Background: In the current study, the authors investigated the distinct role and relative order of protein kinase C (PKC)-delta, adenosine triphosphate-sensitive mitochondrial K+ (mito K-ATP(+)) channels, and reactive oxygen species (ROS) in the signal transduction of sevoflurane-induced cardioprotection and specifically addressed their mechanistic link. Methods: isolated rat trabeculae were preconditioned with 3.8% sevoflurane and subsequently subjected to an ischemic protocol by superfusion of trabeculae with hypoxic, glucose-free buffer (40 min) followed by 60 min of reperfusion. In addition, the acute affect of sevoflurane on PKC-delta and PKC-epsilon translocation and nitrotyrosine formation was established with use of immunofluorescent analysis. The inhibitors chelerythrine (6 mum), rottlerin (1 mum), 5-hydroxydecanoic acid sodium (100 mum), and n-(2-mercaptopropionyl)-glycine (300 mum) were used to study the particular role of PKC, PKC-delta, mito K-ATP(+), and ROS in sevoflurane-related intracellular signaling. Results: Preconditioning of trabeculae with sevoflurane preserved contractile function after ischemia. This contractile preservation was dependent on PKC-delta activation, mito K-ATP(+) channel opening, and ROS production. In addition, on acute stimulation by sevoflurane, PKC-delta but not PKC-epsilon translocated to the sarcolemmal membrane. This translocation was inhibited by PKC inhibitors and ROS scavenging but not by inhibition of mito K-ATP(+) channels. Furthermore, sevoflurane directly induced nitrosylation of sarcolemmal proteins, suggesting the formation of peroxynitrite. Conclusions: in sevoflurane-induced cardioprotection, ROS release but not mito K-ATP(+) channel opening precedes PKC-delta activation. Sevoflurane induces sarcolemmal nitrotyrosine formation, which might be involved in the recruitment of PKC-delta to the cell membrane.