Korean J Physiol Pharmacol.
1997 Dec;1(6):775-781.
Determinant role of the severity of hypoxia in the induction of
reoxygenation injury in cat lung
- Affiliations
-
- 1
Department of Physiol., Kos. University, Coll. Med., Seoul 136-705 South Korea.
Abstract
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Although reoxygenation is the best way to salvage hypoxic tissues,
reduced oxygen species (ROS) generated during reoxygenation are known
to cause further tissue injuries and the induction of heat shock
proteins (HSPs). The present study was undertaken to determine any
causal relationship between the severity of hypoxia and the opposite
outcomes, either beneficial or detrimental, of the subsequent
reoxygenation by measuring the HSP72. To this aim, one group (6 male
cats, 2.5 ~ 3.5 kg) was subjected to a 5-min episode of
hypoventilation (H, ventilation rate: 5/min) for the induction of
slight hypoxia and the other group (6 male cats, 2.4-3.7 kg) was
subjected to a 5-min episode of apnea (A) for severe hypoxia. Each 3
animals from both groups received a 10-min episode of ventilation with
95% O2 (O), whereas the remainder did not. After these procedures, all
animals were allowed to be ventilated within physiological range for 1,
4, or 8 hours (1H, 1HO, 4H, 4HO, 8H, 8HO, 1A, 1AO, 4A, 4AO, 8A and 8AO
groups). Control animals did not receive any manipulation. The arterial
blood pCO2 was significantly higher just after apnea than
hypoventilation, while pO2 and pH were significantly lower just after
apnea than hypoventilation. Western blot analysis revealed that the
magnitude of HSP72 synthesis is larger in 1H, 4H and 8H groups than in
1HO, 4H and 8HO groups, respectively. In contrast, 1AO, 4AO and 8AO
groups more induced HSP72 than 1A, 4A and 8A groups, respectively.
These results suggest that the reoxygenation is beneficial after slight
hypoxia but detrimental after severe hypoxia.