ABSTRACT
<p><b>OBJECTIVE</b>To investigate the influence of a sudden increase of altitudes (within 2500 m) in winter on cardiomyocyte functions in rats.</p><p><b>METHODS</b>Thirty male Wistar rats were randomly divided into groups A (55 m), B (1520 m), and C (2260 m) and subjected to simulated conditions at the indicated altitudes in winter for 3 days. Blood gas analysis, venous blood biochemistry, and measurements of SOD activity and myocardial concentrations of MDA and NO were performed. Histopathological changes in the left ventricle were observed with HE staining and electron microscopy.</p><p><b>RESULTS</b>Blood pH and PCO2 did not differ significantly between the 3 groups, but PO2 and BE in groups B and C decreased significantly compared with those in group A (P<0.01). Compared with group A, the rats in group C showed obviously increased myocardial enzymes, MYB, Tn-I, and MDA contents (P<0.01) with significantly decreased SOD activity (P<0.05); both groups B and C showed significantly decreased NO content in the myocardium (P<0.01). Histopathologically, the myocardial fiber in group C showed irregular alignment, disruption, and mitochondrial expansion.</p><p><b>CONCLUSION</b>A sudden increase of altitude to 2260 m in winter can potentially cause hypoxic cardiomyocyte damage as a result of oxidative and environmental stresses.</p>