Alpha-adrenergic receptors in liver membranes: Delineation with subtype selective radioligands
- 19 January 1981
- journal article
- Published by Elsevier BV in Life Sciences
- Vol. 28 (3), 265-272
- https://doi.org/10.1016/0024-3205(81)90732-3
Abstract
Alpha1 and alpha2 adrenergic receptors have previously been demonstrated in rat liver membranes by competition curves of [3H]dihydroergocryptine ([3H]DHE) with the alpha1 selective antagonist prazosin (B.B. Hoffman, D. Mullikin-Kilpatrick and R.J. Lefkowitz, J. Biol. Chem. :4645–4652, 1980). The present studies have utilized the radioligands [3H]prazosin and [3H]yohimbine to further define alpha receptors in rat liver membranes. [3H]Prazosin was found to label alpha1 receptors whereas [3H]yohimbine labelled alpha2 receptors. The proportion of alpha1 and alpha2 receptors determined directly with these radioligands (79% and 20% respectively) was in good agreement with the proportions determined previously with [3H]DHE. Guanine nucleotides were found to reduce the affinity of the agonist epinephrine at the alpha2 sites labelled by [3H]yohimbine but not at the alpha1 sites labelled by [3H]prazosin. These results have implications for the interpretation of agonist interactions with alpha receptors in liver membranes.Keywords
This publication has 15 references indexed in Scilit:
- Radioligand Binding Studies of Adrenergic Receptors: New Insights into Molecular and Physiological RegulationAnnual Review of Pharmacology and Toxicology, 1980
- Alpha-adrenergic receptor subtypes: Quantitative assessment by ligand bindingLife Sciences, 1979
- Binding characteristics of 3H-prazosin to rat brain α-adrenergic receptorsEuropean Journal of Pharmacology, 1979
- Distinct α-noradrenergic receptors differentiated by binding and physiological relationshipsLife Sciences, 1979
- Direct biochemical demonstration of two types of α-adrenoreceptor in rat brainNature, 1978
- A functional basis for classification of α-adrenergic receptorsLife Sciences, 1977
- Regulation of noradrenaline release by presynaptic receptor systemsReviews of physiology, biochemistry and pharmacology, 1977
- Alpha-noradrenergic receptor binding in mammalian brain: Differential labeling of agonist and antagonist statesLife Sciences, 1976
- Alpha-Adrenergic Receptor Identification by [ 3 H]Dihydroergocryptine BindingScience, 1976
- Presynaptic regulation of catecholamine releaseBiochemical Pharmacology, 1974