Increase of macrophage migration inhibitory factor (MIF) expression in cardiomyocytes during chronic hypoxia

Background: Macrophage migration inhibitory factor (MIF) might play an important role in the myocardium during chronic hypoxia because MIF protects the heart during myocardial ischemia by activating 5'-adenosine monophosphate activated protein kinase (AMPK). Methods: We investigated 35 infants with cyanotic or acyanotic cardiac defects and H9c2 embryonic rat cardiomyocytes to examine the effect of chronic hypoxia on the expression of MIF in vivo and in vitro, respectively. Results: We found out an increase of endogenous cardiac MIF expression positively correlated with degree of hypoxia. Also, AMPK activation was elevated while MIF expression was increased in cells exposed to long periods of hypoxia in vitro. There was no significant difference in the growth ratio of cells cultivated in long periods of hypoxia and normoxia. Conclusions: The expression of MIF is significantly increased in cardiomyocytes exposed to chronic hypoxia, and the activation of AMPK was increased accordingly. (C) 2009 Elsevier B.V. All rights reserved.