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Horm Metab Res 1983; 15(12): 602-606
DOI: 10.1055/s-2007-1018803
© Georg Thieme Verlag, Stuttgart · New York

Triiodothyronamine - A Beta-adrenergic Metabolite of Triiodothyronine?

T. Meyer, R.-D. Hesch
  • Medizinische Hochschule Hannover, Department Innere Medizin und Dermatologie, Abteilung für Klinische Endokrinologie, Hannover, Germany
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Publication History

1981

1983

Publication Date:
14 March 2008 (online)

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Summary

Triiodothyronamine (Triam) is a potential metabolite of triiodothyronine (T3), resulting from decarboxylation of the side-chain. In an attempt to elucidate the physiological properties of Triam we have investigated the binding of Triam to beta-adrenergic receptors, using turkey-erythrocytes and performing binding studies with ((-)(3H)-dihydroalprenolol) ((-)(3H)-DHA) as a specific beta-adrenergic ligand. The inhibition constant Ki for Triam was determined as 5×10-6 M, compared to dopamine (Ki = 1,3×10-2M), norepinephrine (Ki = 3×10-4M), epinephrine (Ki = 5×10-5M) and isoproterenol (Ki = 3×10-6M).

The inhibition of ((-) (3H) DHA)-binding by Triam was further compared with other iodothyronines thyroxine (T4), T3, 3,3′,5′-triiodothyronine (rT3) and 3,3′-diiodo-thyronine (3,3′-T2).

It is concluded that Triam binds to beta-adrenergic receptors like naturally occurring amines but different from typical circulating iodothyronines.

Key-Words:

Triiodothyronamine (Triam) - Triiodothyronine (T 3 ) - Beta-Adrenergic Receptors - Turkey-Erythrocytes