Baboon erythrocyte ghosts contain β-adrenergic receptors

E. E.T. Susanni, F. P. Ross, D. R.L. Scriven, C. Rosendorff

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Abstract

We have used the β-adrenergic antagonist [3H]dihydroalprenolol ([3H]DHA) to identify binding sites on the erythrocyte membrane of the primate Papio ursinus. Analysis of the saturation isotherm revealed binding to be saturable with a maximal number of binding sites of 499 fmol/mg protein. [3H]DHA binds specifically to the erythrocyte ghosts with an apparent dissociation constant (K(d)) of 0.57 ± 0.06 nM. A similar value for K(d) (0.46 ± 0.07 nM) was evaluated from the rate constants of association (0.013 ± 0.003 · nM-1· min-1) and dissociation (0.006 ± 0.001 · min-1). β-adrenergic agonists compete for the binding sites with an order of potency (dl-isoproterenol > l-epinephrine > l-norepinephrine) typical of a β2-adrenergic receptor. Binding was shown to be stereospecific with l-stereoisomers being more potent than their corresponding d-stereoisomers in causing half-maximal inhibition. Isoproterenol stimulated the production of intracellular adenosine 3',5'-cyclic monophosphate (cAMP) in a concentration-dependent manner, maximal levels (1.130 ± 0.358 pmol cAMP/108 cells) being four times the basal levels. The results demonstrate the existence of a large number of β-adrenergic receptors on baboon erythrocyte ghosts.

Original languageEnglish
Pages (from-to)C15-C19
JournalAmerican Journal of Physiology - Cell Physiology
Volume18
Issue number1
DOIs
StatePublished - 1985
Externally publishedYes

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