Effects of thyroid state on adrenoceptor properties

RECENT studies with frog hearts have shown that the adrenoceptors that mediate inotropic responses are altered qualitatively by ambient temperature 1–3 . The characteristics of these receptors changed from β to α when the temperature of the isolated hearts was reduced through a critical range of 17°...

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Bibliographic Details
Published in:Nature (London) 1974-08, Vol.250 (5469), p.779-781
Main Authors: KUNOS, GEORGE, VERMES-KUNOS, ILDIKO, NICKERSON, MARK
Format: Article
Language:English
Subjects:
Adrenergic Agonists - pharmacology
Animals
Humanities and Social Sciences
Hypothyroidism - metabolism
In Vitro Techniques
Isoproterenol - pharmacology
letter
Male
multidisciplinary
Myocardium - metabolism
Norepinephrine - pharmacology
Phenoxybenzamine - pharmacology
Phentolamine - pharmacology
Phenylephrine - pharmacology
Propranolol - pharmacology
Rats
Receptors, Adrenergic
Science
Science (multidisciplinary)
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Summary:RECENT studies with frog hearts have shown that the adrenoceptors that mediate inotropic responses are altered qualitatively by ambient temperature 1–3 . The characteristics of these receptors changed from β to α when the temperature of the isolated hearts was reduced through a critical range of 17°–22° C, which suggested that α and β adrenoceptors represent allosteric conformations of the same structure 3 . Although a change in adenoceptor characteristics qualitatively similar to that found in the frog heart seems to occur in the mammalian myocardium 1,4,5 , the physiological significance of a temperature-induced change is obviously limited in homeothermic species. But, several observations indicate that conditions which promote α -adrenoceptor properties, including cold 1–3 , iodoacetate or fluoroacetate 6 or dinitrophenol 1 , inactivity of skeletal muscle 7 and increased vagal influence on the myocardium 8 , are associated with a decrease in metabolic activity. Therefore, it seemed possible that hypothyroidism would produce similar changes in receptor properties. We report here that the characteristics of adrenoceptors mediating inotropic responses in hypothyroid rats are similar to those in normal hearts at low temperatures.
ISSN:0028-0836
1476-4687
DOI:10.1038/250779a0