Reactive oxygen species precede the epsilon isoform of protein kinase C in the anesthetic preconditioning signaling cascade.
BACKGROUND
Protein kinase C (PKC) and reactive oxygen species (ROS) are known to have a role in anesthetic preconditioning (APC). Cardiac preconditioning by triggers other than volatile anesthetics, such as opioids or brief ischemia, is known to be isoform selective, but the isoform required for APC is not known. The authors aimed to identify the PKC isoform that is involved in APC and to elucidate the relative positions of PKC activation and ROS formation in the APC signaling cascade.


METHODS
Isolated guinea pig hearts were subjected to 30 min of ischemia and 120 min of reperfusion. Before ischemia, hearts were either untreated or treated with sevoflurane (APC) in the absence or presence of the nonspecific PKC inhibitor chelerythrine, the PKC-delta inhibitor PP101, or the PKC-epsilon inhibitor PP149. Spectrofluorometry and the fluorescent probes dihydroethidium were used to measure intracellular ROS, and effluent dityrosine as used to measure extracellular ROS release.


RESULTS
Previous sevoflurane exposure protected the heart against ischemia-reperfusion injury, as previously described. Chelerythrine or PP149 abolished protection, but PP101 did not. ROS formation was observed during sevoflurane exposure and was not altered by any of the PKC inhibitors.


CONCLUSIONS
APC is mediated by PKC-epsilon but not by PKC-delta. Furthermore, PKC activation probably occurs downstream of ROS generation in the APC signaling cascade.
Novalija
Enis
E
Department of Anesthesiology, Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. novalija@mcw.edu
Kevin
Leo G
LG
Camara
Amadou K S
AK
Bosnjak
Zeljko J
ZJ
Kampine
John P
JP
Stowe
David F
DF
D000777:Anesthetics / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology; D004594:Electrophysiology; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004996:Ethidium / Q000031:analogs & derivatives*; D005456:Fluorescent Dyes; D006168:Guinea Pigs; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D007527:Isoenzymes / Q000378:metabolism; D008738:Methyl Ethers / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D009203:Myocardial Infarction / Q000473:pathology; D009206:Myocardium / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D017382:Reactive Oxygen Species / Q000378:metabolism*; D000077149:Sevoflurane; D015398:Signal Transduction / Q000187:drug effects; D014443:Tyrosine / Q000031:analogs & derivatives*; D016277:Ventricular Function, Left / Q000502:physiology
D000777:Anesthetics; D018685:Anesthetics, Inhalation; D005456:Fluorescent Dyes; D007527:Isoenzymes; D008738:Methyl Ethers; D017382:Reactive Oxygen Species; C067883:dihydroethidium; D000077149:Sevoflurane; D014443:Tyrosine; C007543:dityrosine; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D004996:Ethidium