AJP - Cell Physiology, Vol 259, Issue 4 C654-C659, Copyright © 1990 by American Physiological Society
Hepatic cytochrome P-450 in rats submitted to chronic hypobaric hypoxia
L. E. Costa
Instituto de Investigaciones Cardiologicas, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Hepatic cytochrome P-450 content in adaptation to hypobaric hypoxia was
studied in three groups of rats and in their respective controls at sea
level atmospheric pressure. The experimental groups were as follows: 1)
young male and female rats submitted to 4,400 m (simulated altitude) for
6-8 mo, 2) the same animal model of group 1 submitted to 5,500 m (simulated
altitude) for a subsequent period of 2-3 mo, and 3) adult males exposed to
5,500 m for 35 days. Hypoxia caused a marked polycythemia in all three
groups, body weight loss in males of the three groups and at 5,500 m also
in females, whereas liver weight was normal in groups 1 and 2 and slightly
decreased in group 3. Cytochrome P-450 content measured in microsomal
suspensions of groups 1 and 2 was unchanged. In liver homogenates,
cytochrome P-450 content was normal at 4,400 m (group 1) and decreased at
5,500 m (groups 2 and 3). Therefore, endoplasmic reticulum mass, calculated
as the ratio of cytochrome P-450 in the homogenates and in the isolated
microsomes, was unchanged in group 1 (4,400 m) and decreased in group 2
(5,500 m). The content of antioxidant enzymes superoxide dismutase,
catalase, and glutathione peroxidase, measured in liver homogenates of
group 3, were markedly decreased (by 40, 30, and 35%, respectively).
Results do not support the hypothesis that an increase in cytochrome P-450
content plays a role in adaptation to hypoxia.
