AJP - Cell Physiology, Vol 253, Issue 1 C66-C70, Copyright © 1987 by American Physiological Society
Differences in CuZn superoxide dismutase induction in lungs of neonatal and adult rats
M. A. Hass and D. Massaro
The failure of adult rats to survive prolonged exposure to greater than 95%
O2 is generally ascribed to the inability of their lungs to increase
antioxidant enzyme synthesis in response to the oxidant challenge. We
studied the synthesis rate of the antioxidant enzyme CuZn superoxide
dismutase (CuZn SOD) in lungs of adult and neonatal rats exposed to
conditions that alter the lung's oxidant-to-antioxidant balance. Lung CuZn
SOD synthesis in the adult was significantly increased after 24 h of
hyperoxia but fell to control levels after further exposure, whereas in
neonatal lungs an increased rate of synthesis of CuZn SOD was found only
after 72 h of hyperoxia. The adult lung responded to two in vitro oxidant
stresses, [diethyldithiocarbamate exposure and heat (42 degrees C)] with
increases in CuZn SOD synthesis twice the magnitude of those in the
neonatal lung. These data indicate that the adult lung is at least as
capable as the neonatal lung of increasing its synthesis of CuZn SOD in
response to an oxidative stress. However, the inability of the adult lung
to maintain an increased rate of CuZn SOD synthesis during in vivo
hyperoxia may contribute to the poor tolerance of the adult lung to greater
than 95% O2.
