Mg2+ efflux from the isolated perfused rabbit heart is mediated by two states of the beta1-adrenergic receptor

The non-selective beta-adrenergic receptor agonist isoproterenol stimulates Mg(2+) efflux from the perfused heart. The beta-adrenergic receptor subtype governing Mg(2+) efflux was determined in rabbit hearts perfused by the method of Langendorff with Mg(2+)-free Krebs Henseleit buffer. Magnesium eff...

Full description

Saved in:
Bibliographic Details
Published in:Naunyn-Schmiedeberg's archives of pharmacology 2002-11, Vol.366 (5), p.431-439
Main Authors: Young, Lindon, Bercute-Dammann, Andrea, Weis, Margaret T
Format: Article
Language:English
Subjects:
Adrenergic beta-1 Receptor Agonists
Animals
Heart - drug effects
Heart - physiology
Heart - secretion
Isoproterenol - pharmacology
Magnesium - metabolism
Male
Organ Culture Techniques
Perfusion - methods
Rabbits
Receptors, Adrenergic, beta-1 - metabolism
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The non-selective beta-adrenergic receptor agonist isoproterenol stimulates Mg(2+) efflux from the perfused heart. The beta-adrenergic receptor subtype governing Mg(2+) efflux was determined in rabbit hearts perfused by the method of Langendorff with Mg(2+)-free Krebs Henseleit buffer. Magnesium efflux was examined during infusion of isoproterenol (a non-selective beta-adrenergic agonist), dobutamine (beta(1)-selective), salbutamol (beta(2)-selective), BRL37344 in the presence of 200 nM propranolol (beta(3)-selective conditions) or CGP12177 (beta(3)/low affinity state beta(1)-selective). Isoproterenol increased Mg(2+) efflux in a dose-dependent manner, and was the most potent and efficacious agent used. Dobutamine and CGP12177 each significantly increased Mg(2+) efflux, but with markedly different time characteristics. Dobutamine induced significantly less Mg(2+) release than isoproterenol. Although the maximal effect of CGP12177 on Mg(2+) release was 30% less than that of isoproterenol, the difference was not statistically significant. Neither salbutamol nor BRL37344 had any effect on Mg(2+) efflux. These results suggest that isoproterenol-induced Mg(2+) efflux is mediated by both the high and low affinity states of the beta(1)AR, with the low affinity state making the larger contribution.
ISSN:0028-1298