Scintigraphic portrayal of beta receptors in the heart.
J Nucl Med
; 32(7): 1399-407, 1991 Jul.
Article
em En
| MEDLINE
| ID: mdl-1648608
ABSTRACT
Myocardial beta adrenergic receptors play important roles in physiology and disease, but the receptors have not before been portrayed. The beta antagonist, iodocyanopindolol (ICYP), was used to develop a scintigraphic method for depicting the receptors in the living heart. Labeled with 125I, ICYP bound firmly to beta receptors in the rat heart; the data conformed to a mathematical model. In vivo saturation kinetics indicated binding sites with two affinities. Inhibition of ICYP binding by beta antagonists of different potency and different selectivity for beta-1 and beta-2 receptors produced the expected pharmacologic effects. Inhibition by lipophilic and hydrophilic antagonists gave no evidence that ICYP was appreciably bound to internalized receptors. Fractional binding by tracer quantities of (-) ICYP and (+/-) ICYP demonstrated stereospecificity. Labeled with 123I, ICYP bound to the hearts of intact dogs so that scintigraphic tomographs depicted ventricular myocardium. Small doses of beta antagonists selectively reduced the binding of ICYP to lung enabling better visualization of the heart. Thus, 123I-ICYP appears to portray the beta receptors in the living heart, and the characteristics of binding permit the development of mathematical models and lay the basis for quantifying this receptor binding.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Receptores Adrenérgicos beta
/
Coração
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Nucl Med
Ano de publicação:
1991
Tipo de documento:
Article