Tissue Respiratory Studies During Altitude and Cold Exposure

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Abstract
A slight, but significant, decrease in O2 uptake was found for liver slices from rats chronically exposed to altitude, using glycerophosphate as the substrate. Under similar exptl. conditions, respiration of liver slices from the cold-exposed rats was markedly increased. The O2 uptake of liver slices from exercised rats kept at ground level was compared with that from exercised and non-exercised rats maintained at 18,000 ft. for 35-38 days. Liver slices from the exercised altitude-exposed rats had a significantly lower QO2 than did slices from control animals similarly exercised. No significant difference was evident between these groups when the liver slices were allowed to respire in air or 12.5% 02. Similar results were obtained whether expressed on the basis of dry wt. or N content. Cyclophorase activity of liver and kidney was detd. in cold-exposed rats, and of liver, kidney, diaphragm, heart, soleus muscle, gastrocnemium muscle, and brain of altitude-exposed animals. Only the activity of the diaphragm was significantly higher after exposure. Considerable variations in cyclophorase activity were found, using different groups of animals.