Abstract
This study was conducted to more clearly delineate the possible role of endogenous opioid receptors and opioid peptides in general anesthesia-associated hypotension in rats. Exposure to 2% isoflurane in oxygen produced a triphasic change in mean arterial pressure (MAP), including an early phase in which MAP fell by -28.4 +/- 2.2%. The magnitude of this early-phase hypotension was attenuated in rats pretreated with intravenous (i.v.) mu-subtype-selective doses of either naloxone or methylnaloxone but not central doses of the selective mu-opioid antagonist beta-funaltrexamine. This early hypotensive phase was also reduced following i.v. pretreatment with antiserum against methionine-enkephalin but not beta-endorphin. These findings suggest that early-phase isoflurane-induced hypotension may be due to activation of peripheral mu-opioid receptors by an endogenous opioid peptide, possibly related to methionine-enkephalin.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Anesthetics, Inhalation / pharmacology*
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Anesthetics, Intravenous / pharmacology
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Animals
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Antibodies, Blocking / pharmacology
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Blood Pressure / drug effects
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Endorphins / antagonists & inhibitors
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Endorphins / physiology*
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Enkephalin, Methionine / pharmacology
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Hot Temperature
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Hypotension / chemically induced*
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Injections, Intraventricular
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Isoflurane / pharmacology*
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Male
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Naloxone / administration & dosage
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Naloxone / pharmacology
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Naltrexone / adverse effects
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Naltrexone / analogs & derivatives*
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Naltrexone / pharmacology
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Narcotic Antagonists / pharmacology
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Pain Measurement / drug effects
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Rats
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Rats, Sprague-Dawley
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Reaction Time / drug effects
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Receptors, Opioid / physiology*
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Urethane / pharmacology
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beta-Endorphin / pharmacology
Substances
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Anesthetics, Inhalation
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Anesthetics, Intravenous
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Antibodies, Blocking
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Endorphins
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Narcotic Antagonists
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Receptors, Opioid
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Naloxone
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Urethane
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Enkephalin, Methionine
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Naltrexone
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beta-Endorphin
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beta-funaltrexamine
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Isoflurane