[Involvement of potassium channel in hemin-induced cardioprotection in rat hearts].
To investigate the effects of heme oxygenase 1 inducer hemin on protection of ischemia-reperfusion injury in rats and its mechanisms.



The Langendorff model of isolated rat heart was used; the left anterior descending coronary artery was occluded for 30 min and subsequently reperfused for 2 h. Then the ventricular function and infarct size were measured.



Hemin preconditioning prevented the increase in LVEDP, decrease in LVDP and +/- dp/dt(max) in the isolated ischemia-reperfusion rat hearts. The leakage of LDH and CK in the coronary effluent was significantly declined in hemin-treated rat hearts. And the infarct size was also reduced. Administration of a blocker of mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) 5-HD (5 mg/kg) before hemin preconditioning increased the LVEDP, and reduced the LVDP and +/- dp/dt(max). The leakage of LDH and CK in the coronary effluent and the infarct size were also increased compared with only hemin-treated rat hearts. Pretreatment of the rats with a blocker of sarcolemmal ATP-sensitive potassium channel (sarcK(ATP)) HMR-1098 (6 mg/kg) before hemin preconditioning also abolished the protective effect. Infusion of paxilline (1 micromol/L), a blocker of calcium activated potassium channel (K(Ca)) for 10 min before ischemia/reperfusion led to larger infarct size and poorer myocardial performance as compared with the hemin group. The leakage of LDH and CK in the coronary effluent was also increased.



Both mitoK(ATP)and sarcK(ATP)channels activation are required for the delayed cardioprotection induced by hemin. The opening of K(Ca) channels-dependent mechanism may be involved in the protection.
Xu
He-Jing
HJ
Department of Physiology, College of Medicine, Zhejiang University, Hangzhou 310058, China.
Zhu
Li
L
Wang
Yang
Y
Shen
Fa-Rong
FR
Jin
Hong-Feng
HF
Shen
Yue-Liang
YL
Chen
Ying-Ying
YY
D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000096:biosynthesis; D006427:Hemin / Q000494:pharmacology*; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods; D008297:Male; D009203:Myocardial Infarction / Q000378:metabolism; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D002316:Cardiotonic Agents; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; C117780:mitochondrial K(ATP) channel; D006427:Hemin; D051547:Heme Oxygenase-1