MITOCHONDRIAL CYTOCHROME CONCENTRATIONS IN RAT-HEART AND LIVER AS A CONSEQUENCE OF DIFFERENT HYPOXIC PERIODS

Rat heart and liver cytochrome concentrations were determined after 3 hypoxic conditions (atmospheric pressure 50.5 kPa, 40.8 kPa and 38.0 kPa) lasting 1 wk and 2 wk. The heart showed clear hypertrophy which was 38% in most severe hypoxia (38 kPa, 2 wk). A small decline in the liver weight to body weight ratio was observed, this decrease being 21% in the most severe case. During the hypoxic periods the mitochondrial cytochrome concentration decreased. This phenomenon was more obvious when the degree of hypoxia was increased and more pronounced after 2 wk than 1 wk. The heart and liver showed quite similar patterns in this respect. In most severe hypoxia the decreases in the liver were 29% for cytochrome aa3, 30% for cytochrome b, 20% for cytochrome c and 15% for cytochrome c1, with the concentrations expressed on mitochondrial protein basis. The corresponding values in the heart were 31%, 43%, 28% and 22%. In mammals the mitochondrial cytochrome content probably varies according to the amount of O2 available.