title: Mitochondrial big conductance KCa channel and cardioprotection in infant rabbit heart.
abstract: Chronic hypoxia increases resistance to myocardial ischemia in infants. Activation of the mitochondrial big conductance Ca(2+) -sensitive K channel (mitoBKCa) has been shown to be protective in adult hearts; however, its role in infant hearts is unknown. Hearts from normoxic or hypoxic infant rabbits were perfused with a mitoKCa opener, NS1619, or blocker Paxilline before ischemia and reperfusion. Hypoxic hearts were more resistant to ischemia than normoxic hearts as manifested by a reduction in infarct size (9 +/- 5% versus 14 +/- 5%) and an increase in recovery of left ventricular developed pressure (LVDP) (69 +/- 7% versus 51 +/- 2%). NS1619 decreased infarct size in normoxic hearts from 14 +/- 5% to 10 +/- 5% and increased recovery of LVDP from 51 +/- 2% to 65 +/- 4%, but it had no effect on hypoxic hearts. Paxilline did not affect normoxic or hypoxic hearts. Activation of mitoBKCa protects normoxic infant rabbit hearts; however, cardioprotection by chronic hypoxia in infant rabbits does not appear involve mitoBKCa.
authors.affiliation: Surgery-Division of Pediatric Surgery, Medical College of Wisconsin, Mikwaukee, WI 53226, USA. yangshi@mcw.edu
authors.forename: Yang
authors.initials: Y
authors.lastname: Shi
authors.forename: Ming Tao
authors.initials: MT
authors.lastname: Jiang
authors.forename: Jidong
authors.initials: J
authors.lastname: Su
authors.forename: William
authors.initials: W
authors.lastname: Hutchins
authors.forename: Eugene
authors.initials: E
authors.lastname: Konorev
authors.forename: John E
authors.initials: JE
authors.lastname: Baker
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001562:Benzimidazoles / Q000494:pharmacology; D003326:Coronary Circulation / Q000187:drug effects; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology; D007211:Indoles / Q000494:pharmacology; D019157:Ischemic Preconditioning, Myocardial; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000378:metabolism; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010477:Perfusion; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000819:agonists; D011817:Rabbits; D016276:Ventricular Function / Q000187:drug effects
chemical_list: D001562:Benzimidazoles; D007211:Indoles; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C086491:NS 1619; C048220:paxilline