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Mg2+ efflux from the isolated perfused rabbit heart is mediated by two states of the β1-adrenergic receptor

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Abstract.

The non-selective β-adrenergic receptor agonist isoproterenol stimulates Mg2+ efflux from the perfused heart. The β-adrenergic receptor subtype governing Mg2+ efflux was determined in rabbit hearts perfused by the method of Langendorff with Mg2+-free Krebs Henseleit buffer. Magnesium efflux was examined during infusion of isoproterenol (a non-selective β-adrenergic agonist), dobutamine (β1-selective), salbutamol (β2-selective), BRL37344 in the presence of 200 nM propranolol (β3-selective conditions) or CGP12177 (β3/low affinity state β1-selective). Isoproterenol increased Mg2+ efflux in a dose-dependent manner, and was the most potent and efficacious agent used. Dobutamine and CGP12177 each significantly increased Mg2+ efflux, but with markedly different time characteristics. Dobutamine induced significantly less Mg2+ release than isoproterenol. Although the maximal effect of CGP12177 on Mg2+ release was 30% less than that of isoproterenol, the difference was not statistically significant. Neither salbutamol nor BRL37344 had any effect on Mg2+ efflux. These results suggest that isoproterenol-induced Mg2+ efflux is mediated by both the high and low affinity states of the β1AR, with the low affinity state making the larger contribution.

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Young, L., Bercute-Dammann, A. & Weis, M.T. Mg2+ efflux from the isolated perfused rabbit heart is mediated by two states of the β1-adrenergic receptor. Naunyn-Schmiedeberg's Arch Pharmacol 366, 431–439 (2002). https://doi.org/10.1007/s00210-002-0628-9

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  • DOI: https://doi.org/10.1007/s00210-002-0628-9

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