The role of mitochondrial and sarcolemmal K(ATP) channels in canine ethanol-induced preconditioning in vivo.
Chronic consumption of small doses of ethanol protects myocardium from ischemic injury. We tested the hypothesis that mitochondrial and sarcolemmal adenosine triphosphate-dependent potassium (K(ATP)) channels mediate these beneficial effects. Dogs (n = 76) were fed with ethanol (1.5 g/kg) or water mixed with dry food bid for 6 or 12 wk, fasted overnight before experimentation, and instrumented for measurement of hemodynamics. Dogs received intracoronary saline (vehicle), 5-hydroxydecanoate (a mitochondrial K(ATP) channel antagonist; 6.75 mg/kg over 45 min), or HMR-1098 (a sarcolemmal K(ATP) channel antagonist; 45 microg/kg over 45 min) and were subjected to a 60 min coronary artery occlusion followed by 3 h of reperfusion. A final group of dogs was pretreated with ethanol and chow for 6 wk before occlusion and reperfusion. Myocardial infarct size and transmural coronary collateral blood flow were measured with triphenyltetrazolium chloride staining and radioactive microspheres, respectively. The area at risk of infarction was similar between groups. A 12-wk pretreatment with ethanol significantly reduced infarct size to 13% +/- 2% (mean +/- SEM; n = 8) of the area at risk compared with control experiments (25% +/- 2%; n = 8), but a 6-wk pretreatment did not (21% +/- 2%; n = 8). 5-hydroxydecanoate and HMR-1098 abolished the protective effects of 12-wk ethanol pretreatment (24% +/- 2% and 29% +/- 3%, respectively; n = 8 for each group) but had no effect in dogs that did not receive ethanol (22% +/- 2% and 23% +/- 4%, respectively; n = 8 for each group). No differences in hemodynamics or transmural coronary collateral blood flow were observed between the groups. The results indicate that mitochondrial and sarcolemmal K(ATP) channels mediate ethanol-induced preconditioning in dogs independent of alterations in systemic hemodynamics or coronary collateral blood flow.


CONCLUSIONS
Mitochondrial and sarcolemmal K(ATP) channels mediate ethanol-induced preconditioning independent of alterations in systemic hemodynamics or coronary collateral perfusion in vivo.
Pagel
Paul S
PS
Department of Anesthesiology, Medical College of Wisconsin and Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin 53226, USA. pspage@mcw.edu
Krolikowski
John G
JG
Kehl
Franz
F
Mraovic
Boris
B
Kersten
Judy R
JR
Warltier
David C
DC
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D003326:Coronary Circulation; D003652:Decanoic Acids / Q000494:pharmacology; D004285:Dogs; D000431:Ethanol / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects; D006880:Hydroxy Acids / Q000494:pharmacology; D019157:Ischemic Preconditioning, Myocardial; D008929:Mitochondria, Heart / Q000378:metabolism*; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000517:prevention & control; D009206:Myocardium / Q000378:metabolism*; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism*
D001549:Benzamides; D003652:Decanoic Acids; D006880:Hydroxy Acids; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D000431:Ethanol; C052853:5-hydroxydecanoic acid; D000255:Adenosine Triphosphate; C410297:HMR 1098