Lipid emulsion rapidly restores contractility in stunned mouse cardiomyocytes: a comparison with therapeutic hypothermia.
OBJECTIVE
Cooling following cardiac arrest can improve survival significantly. However, delays in achieving target temperature may decrease the overall benefits of cooling. Here, we test whether lipid emulsion, a clinically approved drug reported to exert cardioprotection, can rescue heart contractility in the setting of delayed cooling in stunned mouse cardiomyocytes.


METHODS
Cell culture study.


METHODS
Academic research laboratory.


METHODS
Cardiomyocytes isolated from 1- to 2-day-old C57BL6 mice.


METHODS
Cardiomyocytes were exposed to 30 minutes of ischemia followed by 90 minutes of reperfusion and 10 minutes of isoproterenol with nine interventions: 1) no additional treatment; 2) intraischemic cooling at 32 °C initiated 10 minutes prior to reperfusion; 3) delayed cooling started 20 minutes after reperfusion; 4) lipid emulsion + delayed cooling; 5) lipid emulsion (0.25%) administered at reperfusion; 6) lipid emulsion + intraischemic cooling; 7) delayed lipid emulsion; 8) lipid emulsion + delayed cooling + Akt inhibitor (API-2, 10 µM); and 9) lipid emulsion + delayed cooling + Erk inhibitor (U0126, 10 µM). Inhibitors were given to cells 1 hour prior to ischemia.


RESULTS
Contractility was recorded by real-time phase-contrast imaging and analyzed with pulse image velocimetry in MATLAB (Mathworks, Natick, MA). Ischemia diminished cell contraction. The cardioprotective effect of cooling was diminished when delayed but was rescued by lipid emulsion. Further, lipid emulsion on its own improved recovery of the contractility to a greater extent as intraischemic cooling. However, cotreatment of lipid emulsion and intraischemic cooling did not further improve the recovery compared to either treatment alone. Furthermore, Akt and Erk inhibitors blocked lipid emulsion-induced protection.


CONCLUSIONS
Lipid emulsion improved contractility and rescued contractility in the context of delayed cooling. This protective effect required Akt and Erk signaling. Lipid emulsion might serve as a treatment or adjunct to cooling in ameliorating myocardial ischemia/reperfusion injury.
1Department of Emergency Medicine, University of Illinois Hospital & Health Sciences System, Chicago, IL. 2Department of Anesthesiology, University of Illinois Hospital & Health Sciences System, Chicago, IL. 3Division of Research, Jesse Brown Veterans Affairs Medical Center, Chicago, IL. 4Department of Emergency Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Jing
J
Li
Michael
M
Fettiplace
Sy-Jou
SJ
Chen
Benjamin
B
Steinhorn
Zuohui
Z
Shao
Xiangdong
X
Zhu
Changqing
C
Li
Shaun
S
Harty
Guy
G
Weinberg
Terry L
TL
Vanden Hoek
D000818:Animals; D002070:Butadienes / Q000494:pharmacology*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D002747:Chlorpropamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D004195:Disease Models, Animal; D007036:Hypothermia, Induced / Q000379:methods*; D007511:Ischemia / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009119:Muscle Contraction / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000473:pathology*; D009570:Nitriles / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors; D013997:Time Factors; D000096926:Benzenesulfonamides
D002070:Butadienes; D002316:Cardiotonic Agents; D002747:Chlorpropamide; D020928:Mitogen-Activated Protein Kinases; D009570:Nitriles; D051057:Proto-Oncogene Proteins c-akt; C111224:API 2; D000096926:Benzenesulfonamides; C113580:U 0126