Oxygen Tensions in the Deep Gray Matter of Rats Exposed to Hyperbaric Oxygen
Selective necrosis of neurons and nuclei consistently occurs within the central nervous system (CNS) of rats paralyzed by repeated 1 hour exposures to 5 atmospheres of oxygen.l The distribution of the lesions differs from those of hypoxia in the same animal species. Excessive oxygen inhibits many enzymes vital to cellular metabolism in the CNS and it is reasonable to hypothesize that the neuronal necrosis produced by hyperbaric oxygen exposure is related to elevated tissue oxygen tensions. However, hyperbaric oxygen notedly produces cerebral vasospasm and a reduction in cerebral blood flow, and regional ischemia has been a tenable hypothesis for the occurrence of the CNS lesions. This latter mechanism seems unlikely because unilateral carotid artery ligation protects the ipsilateral but not the contralateral cerebral hemisphere from the occurrence of the oxygen induced lesions.2 (see Fig. 1)
KeywordsOxygen Tension Globus Pallidus Hyperbaric Oxygen Cerebral Vasospasm Central Nervous System Lesion
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