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Postjunctional α-adrenoceptors

α1 and α2 subtypes in rat vasculature in vitro and in vivo

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Summary

The postsynaptic α-adrenoceptors in rat aorta and in pithed rat were investigated according to their sensitivity to nine α-adrenergic agonists and to the selective antagonists yohimbine (α2) and prazosin (α1) and the non-selective one, phentolamine. In addition, in radioligand binding studies, the affinity and selectivity of the drugs were determined on rat cerebral cortex using [3H] yohimbine and [3H] prazosin.

On rat aorta, prazosin is 1,000 times more potent than yohimbine against each α-adrenoceptor agonist, whether α1- or α2-selective. Rat aorta probably contains only α1-adrenoceptors.

Pressor effects in pithed rats are mediated by post-junctional α1- and α2-adrenoceptors. The dose-response curve for α-methylnorepinephrine in the presence of prazosin, using Hofstee's plots, revealed α1- and α2-adrenoceptors, respective proportions being 80.5 and 19.5%

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Authors and Affiliations

  1. Institut de Pharmacologie (CNRS ERA 142, INSERM U. 206), Faculte de Médecine, 11 rue Humann, F-67000, Strasbourg, France

    N. Decker, J. D. Ehrhardt, G. Leclerc & J. Schwartz

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  1. N. Decker
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  2. J. D. Ehrhardt
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  3. G. Leclerc
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  4. J. Schwartz
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Decker, N., Ehrhardt, J.D., Leclerc, G. et al. Postjunctional α-adrenoceptors. Naunyn-Schmiedeberg's Arch. Pharmacol. 326, 1–6 (1984). https://doi.org/10.1007/BF00518771

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  • DOI: https://doi.org/10.1007/BF00518771

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