Effects of increased left ventricular work, hypoxia, or coronary ligation on hearts from rats at high altitude

Abstract

Isolated perfused hearts from rats acclimatized to Jungfraujoch (altitude 3454 m) were less resistant to the effects of high levels of heart work or mild hypoxia than hearts from litter mates reared at Geneva (340 m). After coronary artery ligation hearts from acclimatized rats were better able to maintain tissue contents of ATP, phosphocreatine and glycogen. Increased biochemical resistance to ischemia was explained by relative increase in coronary flow rate. Exposure to high altitude probably helps to protect the heart against coronary occlusion by increased resistance developing from increased sensitivity to high levels of heart work and hypoxia.