[abstract] A NOVEL CATALYTIC ANTIOXIDANT PROTECTS AGAINST HYPERBARIC OXYGEN INDUCED CONVULSIONS.

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[abstract] A NOVEL CATALYTIC ANTIOXIDANT PROTECTS AGAINST HYPERBARIC OXYGEN INDUCED CONVULSIONS.

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Title: [abstract] A NOVEL CATALYTIC ANTIOXIDANT PROTECTS AGAINST HYPERBARIC OXYGEN INDUCED CONVULSIONS.
Author: Piantadosi, CA; Day, BJ; Crapo, JD; Demchenko, IT
Abstract: BACKGROUND: Extreme hyperoxia causes a sustained increase in the formation of superoxide anion (O2-) that appears to contribute to oxygen convulsions. We have assessed the effects of a catalytically active manganese porphyrin antioxidant (code: AEOL-10113) to protect against seizures induced by hyperbaric oxygen (HBO2). METHODS: Awake or anesthetized SD rats were exposed to O2 at 5 ATA. Blood flow in the right striatum of anesthetized animals was measured by hydrogen clearance. NO metabolites (NOx) and 3-nitrotyrosine (3-NT), as indicators of NO and ONOO- formation, were measured in the left striatum of the same rats by microdialysis and analyzed by chemiluminescence and HPLC respectively. Blood pressure, EEG and temperature were monitored. Blood gases were controlled. All measurements were made during HBO-exposure with or without administration of AEOL-10113. Antioxidant drug was given to awake rats subcutaneously (0.5 mg/kg) or to anesthetized animals intracerebroventricularly (500 ng) before hyperbaric exposure. RESULTS: Awake rats treated with antioxidant were more tolerant (10percent mortality) to CNS O2 toxicity than control animals (50percent mortality). Oxygen seizures were observed only in 2 of 10 rats treated with antioxidant while 8 of 10 animals of control group displayed tonic-clonic convulsions during O2 exposure at 5 ATA. Anesthetized rats treated with antioxidant and exposed to O2 at 5 ATA showed no EEG spikes, as a sign of CNS O2 toxicity, while seizure latency for control rats was 51+/-7 min. Cerebral vasoconstriction in response to HBO2 was less pronounced in treated than in control animals but a secondary increase in blood flow was observed in both groups of rats. NOx increased in treated and control rats during HBO2 exposure while significant 3-NT formation was observed in control animals only. CONCLUSIONS: A synthetic catalytic antioxidant had marked protective effects against CNS O2 toxicity when given subcutaneously or intracerebroventricularly. Possible protective mechanisms involve more rapid intra-and extracellular dismutation of superoxide and elimination of ONOO- production.
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/1048
Date: 2001

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  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

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