Cardiovascular Effects of Ethanol in Rats Selectively Bred for High or Low Sensitivity to the Hypnotic Effects of Ethanol

Authors

  • Kàroly Varga,

    Corresponding author
    1. Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia.
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  • George Kunos

    1. Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia.
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  • This work was supported by the National Institutes of Health Grant AA09719 (to G.K.).

Reprint requests: Karoly Varga, M.D., Ph.D., Department of Pharmacology and Toxicology, Medical College of Virginia, Box 980613, Richmond, VA 23298.

Abstract

The cardiovascular effects of acute ethanol administration were studied in rats selectively bred for high (HAS) or low sensitivity (US) to the acute hypnotic effect of ethanol. In chronically cannulated, conscious animals, the intravenous administration of 1 g/kg of ethanol caused moderate hypotension and tachycardia in both HAS and LAS rats. The phenylephrine-induced reflex bradycardia and the baroreflex slope were significantly reduced by ethanol only in HAS and not in LAS rats. In urethane-anesthetized HAS rats, the baroreflex inhibitory action of ethanol was present under control conditions, but it was absent after depletion of endogenous GABA by treatment of the rats with 100 mg/kg of 3-mercaptopropionate. These findings confirm the role of endogenous GABA in the baroreflex inhibitory action of ethanol, and are compatible with the documented differential sensitivity of the GABA, receptor complex to ethanol in HAS and LAS rats.

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