Urocortin prevents mitochondrial permeability transition in response to reperfusion injury indirectly by reducing oxidative stress.
Urocortin (UCN) protects hearts against ischemia and reperfusion injury whether given before ischemia or at reperfusion. Here we investigate the roles of PKC, reactive oxygen species, and the mitochondrial permeability transition pore (MPTP) in mediating these effects. In Langendorff-perfused rat hearts, acute UCN treatment improved hemodynamic recovery during reperfusion after 30 min of global ischemia; this was accompanied by less necrosis (lactate dehydrogenase release) and MPTP opening (mitochondrial entrapment of 2-[(3)H]deoxyglucose). UCN pretreatment protected mitochondria against calcium-induced MPTP opening, but only if the mitochondria had been isolated from hearts after reperfusion. These mitochondria also exhibited less protein carbonylation, suggesting that UCN decreases levels of oxidative stress. In isolated adult and neonatal rat cardiac myocytes, both acute (60 min) and chronic (16 h) treatment with UCN reduced cell death following simulated ischemia and re-oxygenation. This was accompanied by less MPTP opening as measured using tetramethylrhodamine methyl ester. The level of oxidative stress during reperfusion was reduced in cells that had been pretreated with UCN, suggesting that this is the mechanism by which UCN desensitizes the MPTP to reperfusion injury. Despite the fact that we could find no evidence that either PKC-epsilon or PKC-alpha translocate to the mitochondria following acute UCN treatment, inhibition of PKC with chelerythrine eliminated the effect of UCN on oxidative stress. Our data suggest that acute UCN treatment protects the heart by inhibiting MPTP opening. However, the mechanism appears to be indirect, involving a PKC-mediated reduction in oxidative stress.
Townsend
Paul A
PA
Human Genetics Division, University of Southampton, Southampton, UK. p.a.townsend@soton.ac.uk
Davidson
Sean M
SM
Clarke
Samantha J
SJ
Khaliulin
Igor
I
Carroll
Christopher J
CJ
Scarabelli
Tiziano M
TM
Knight
Richard A
RA
Stephanou
Anastasis
A
Latchman
David S
DS
Halestrap
Andrew P
AP
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D053119:Benzophenanthridines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002316:Cardiotonic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology* / Q000627:therapeutic use; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D033681:Mitochondrial Membrane Transport Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D009200:Myocardial Contraction / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D009336:Necrosis; D018384:Oxidative Stress / Q000187:drug effects*; D050050:Protein Carbonylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D054832:Urocortins; D017725:Ventricular Pressure / Q000187:drug effects
D000470:Alkaloids; D000975:Antioxidants; D053119:Benzophenanthridines; D002316:Cardiotonic Agents; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; D054832:Urocortins; D003346:Corticotropin-Releasing Hormone; C016299:chelerythrine; D011493:Protein Kinase C; D002118:Calcium