Moderate hypothermia (30 degrees C) maintains myocardial integrity and modifies response of cell survival proteins after reperfusion.
Hypothermia preserves myocardial function, promotes signaling for cell survival, and inhibits apoptotic pathways during 45-min reperfusion. We tested the hypothesis that signaling at the transcriptional level is followed by corresponding proteomic response and maintenance of structural integrity after 3-h reperfusion. Isolated hearts were Langendorff perfused and exposed to mild (I group; n = 6, 34 degrees C) or moderate (H group; n = 6, 30 degrees C) hypothermia during 120-min total ischemia with cardioplegic arrest and 180-min 37 degrees C reperfusion. Moderate hypothermia suppressed anaerobic metabolism during ischemia and significantly diminished left ventricular end-diastolic pressure at the end of ischemia from 52.7 +/- 3.3 (I group) to 1.8 +/- 0.9 (H group) mmHg. Unlike the I group, which showed poor cardiac function and high left ventricular pressure, the H group showed preservation of myocardial function, coronary flow, and oxygen consumption. Compared with normal control hearts without ischemia (n = 5), histological staining in the I group showed marked disarray and fragmentation of collagen network (score 4-5), while the H group showed preserved collagen integrity (score 0-1). The apoptosis-linked tumor suppressor protein p53 was expressed throughout the I group only (score 4-5). The H group produced elevated expression for hypoxia-inducible factor 1alpha and heme oxygenase 1, but minimally affected vascular endothelial growth factor expression. The H group also elevated expression for survival proteins peroxisomal proliferator-activated receptor-beta and Akt-1. These results show in a constant left ventricular volume model that moderate hypothermia (30 degrees C) decreases myocardial energy utilization during ischemia and subsequently promotes expression of proteins involved in cell survival, while inhibiting induction of p53 protein. These data also show that 34 degrees C proffers less protection and loss of myocardial integrity.
Pediatric Cardiology, Univ. of Washington, CHRMC/W4841, 4800 Sand Point Way NE, Seattle, WA 98105-0371, USA. xh@u.washington.edu
Xue-Han
XH
Ning
Emil Y
EY
Chi
Norman E
NE
Buroker
Shi-Han
SH
Chen
Cheng-Su
CS
Xu
Ying-Tzang
YT
Tien
Outi M
OM
Hyyti
Ming
M
Ge
Michael A
MA
Portman
D000818:Animals; D002470:Cell Survival; D003094:Collagen / Q000378:metabolism; D003326:Coronary Circulation; D004195:Disease Models, Animal; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D007036:Hypothermia, Induced; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D010101:Oxygen Consumption; D048068:PPAR-beta / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D015398:Signal Transduction / Q000235:genetics; D013997:Time Factors; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D047908:Intracellular Signaling Peptides and Proteins; D048068:PPAR-beta; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D042461:Vascular Endothelial Growth Factor A; D003094:Collagen; D051547:Heme Oxygenase-1; D051057:Proto-Oncogene Proteins c-akt