Objective    In the heart

autophagy is important for the turnover of organelles at low basal levels under normal conditions

but is upregulated in response to stresses such as ischemia/reperfusion and in cardiovascular diseases such as heart failure. It can prevent the heart from injury under stress conditions. This study was designed to test the hypothesis that autophagy would be upregulated in the myocardium of children with cyanotic congenital cardiac defects.     Methods    Eighteen children with cyanotic (n=10) or acyanotic cardiac defects (n=8) who were admitted in our hospital from October 2008 to April 2009 and received surgical treatment were investigated. Samples from the right ventricular myocardium taken immediately after aortic clamping were morphologically studied with transmission electron microscopy for the ultrastructure. Microtubule-associated protein 1 light chain 3 (LC-3) was detected by Western blot analysis in the obtained samples.     Results    Children with cyanotic cardiac defects had higher oxyhemoglobin saturation before operation than those with acyanotic cardiac defects. Electron microscopy showed that the former group had more mitochondria

disordered arrangement

swollen endoplasmic reticulum and typical autophagosomes in the myocardial cytosol. LC3-II were significantly elevated  in patients with cyanotic compared with those with acyanotic congenital cardiac defects (P0.01).     Conclusion    Chronic hypoxemia is associated with the induction of autophagy. Thus

up-regulated autophagy might particularly participate in myocardial adaption to chronic hypoxia in children with cyanotic congenital cardiac defects.