Abstract
Graded caval occlusion in conscious rabbits caused a biphasic response. Phase I was characterized by a fall in conductance so that arterial pressure was maintained. When cardiac output had fallen to 69 +/- 2% of its baseline level, phase II supervened. During phase II, conductance rose abruptly and arterial pressure fell to a life-threatening level (< 40 mmHg). Centrally administered delta-opioid receptor antagonists prevented the occurrence of phase II. The relative order of potency was 7-benzylidene-naltrexone (BNTX, delta 1-selective) > N,N-diallyl-Tyr-Aib-Phe-Leu-OH (ICI 174,864) > naltrindole (delta 2-selective). It is concluded that a central delta 1-opioid receptor is involved in the onset of the second decompensatory phase of the haemodynamic response to haemorrhage.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Benzylidene Compounds / pharmacology
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Blood Pressure / drug effects
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Blood Pressure / physiology
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Cardiac Output / drug effects
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Cardiac Output / physiology
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Enkephalin, Leucine / analogs & derivatives
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Enkephalin, Leucine / pharmacology
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Hemodynamics / drug effects*
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Hemorrhage / physiopathology
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Naltrexone / analogs & derivatives
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Naltrexone / pharmacology
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Narcotic Antagonists / pharmacology*
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Rabbits
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Receptors, Opioid, delta / antagonists & inhibitors
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Receptors, Opioid, delta / physiology*
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Shock / physiopathology*
Substances
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Benzylidene Compounds
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Narcotic Antagonists
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Receptors, Opioid, delta
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7-benzylidenenaltrexone
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Enkephalin, Leucine
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Naltrexone
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N,N-diallyl-tyrosyl-alpha-aminoisobutyric acid-phenylalanyl-leucine
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naltrindole