Abstract
This study assessed the state of melatonin MT(1) receptor coupling in sections of male rat caudal arteries by [35S]GTPgammaS binding autoradiography. The melatonin MT(1) receptor inverse agonist 4-phenyl-2-propionamidotetraline (4P-PDOT) (0.1-1 microM) significantly decreased [35S]GTPgammaS binding compared to basal, strongly suggesting the presence of constitutively active receptors. Formation of constitutively active receptors during subjective day, when the levels of melatonin are low, may be a physiological mechanism by which the organism maintains vascular tone.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Arteries / drug effects
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Arteries / metabolism*
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Autoradiography
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Binding, Competitive / drug effects
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Dose-Response Relationship, Drug
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Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
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Male
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Melatonin / pharmacology
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Rats
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Rats, Inbred F344
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Receptors, Cell Surface / metabolism*
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Receptors, Cytoplasmic and Nuclear / metabolism*
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Receptors, Melatonin
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Sulfur Radioisotopes
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Tetrahydronaphthalenes / pharmacology
Substances
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4-phenyl-2-propionamidotetraline
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Receptors, Cell Surface
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Receptors, Cytoplasmic and Nuclear
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Receptors, Melatonin
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Sulfur Radioisotopes
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Tetrahydronaphthalenes
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Guanosine 5'-O-(3-Thiotriphosphate)
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Melatonin