Journal of Applied Physiology, Vol 76, Issue 3 1073-1076, Copyright © 1994 by American Physiological Society
Beta-carotene and CNS oxygen toxicity in rats
N. Bitterman, Y. Melamed and A. Ben-Amotz
Israeli Naval Hyperbaric Institute, Haifa.
Beta-carotenes are reported to be potent free radical quenchers, singlet
oxygen scavengers, and lipid antioxidants. Oxygen free radicals that are
produced in excess during exposure to oxygen at high pressures and
overwhelm the body's normal antioxidant defense systems seem to mediate the
hyperoxic insult. We decided to test the possible protective effect against
central nervous system oxygen toxicity of a natural beta-carotene composed
of equal amounts of the all-trans and 9-cis isomers obtained from the
unicellular halotolerant alga Dunaliella bardawil. Rats implanted with
chronic cortical electrodes for continuous electroencephalogram monitoring
were fed on ground commercial food enriched with natural beta-carotene (1
g/kg diet). On completion of 1 wk of the diet, the rats were exposed to 0.5
MPa oxygen and then their livers were removed for beta-carotene and vitamin
A analysis. A significant increase was noted in the latent period preceding
oxygen seizures in the group of rats in which the diet was supplemented by
natural beta-carotene compared with rats given a normal diet (38.5 +/- 3.4
vs. 16.8 +/- 1.8 min; P < 0.05). Further experiments are required to
evaluate the potential benefit of supplementing the diet of divers and
patients exposed to high pressures of oxygen with the beta-carotene-rich D.
bardawil.
