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- Title
Histoautoradiographic Localization of (-)-<sup>3</sup>H-Dihydroalprenolol in Rabbit Aorta.
- Authors
Amenta, Francesco; Cavallotti, Carlo; De Rossi, Marco
- Abstract
The distribution pattern of (-)-3H-dihydroalprenolol (3H-DHA) binding sites within the thoracic and abdominal aorta was studied using a histoautoradiographic technique. Frozen sections of rabbit aorta were incubated with 3H-DHA in the presence or absence of 1 μmol/l (-)-propranolol and of increasing concentrations of various adrenergic agents. After washing, the same sections were placed in scintillation vials and counted to evaluate the pharmacological characteristics of 3H-DHA binding or processed for histoautoradiography. 3H-DHA was bound by sections of the rabbit aorta in a manner consistent with the presence of β-adrenoceptors. The binding was reversible, saturable and of high affinity, with a dissociation constant Kd of 1.0 nmol/l and a maximum binding capacity Bmax of 17 fmol/mg tissue (wet weight). It was inhibited only by β-adrenoceptor blocking drugs. Histoautoradiographic studies revealed that β-adrenoceptors are located primarily in the media and then in the intima. The lowest density of 3H-DHA was found in the adventitia. The distribution pattern of β-adrenoceptors in the media suggests the possible existence of two groups of β-adrenoceptors within this layer of the aorta. The first group was found in the outer portions of the media and may be controlled by the adrenergic nerves that supply the artery. The second group was found in the portions of the media closest to the intima and is likely under the control of catecholamines coming from the lumen of the aorta. Copyright © 1985 S. Karger AG, Basel
- Publication
Pharmacology, 1985, Vol 30, Issue 3, p160
- ISSN
0031-7012
- Publication type
Article
- DOI
10.1159/000138065