PMID: 6296703Nov 1, 1982Paper

Competitive and non-competitive interactions between specific ligands and beta-adrenoceptors in living cardiac cells

Naunyn-Schmiedeberg's Archives of Pharmacology
H PorzigH Reuter

Abstract

We have used primary cultures of hearts from newborn rats to study beta-adrenoceptor properties in living myocardial cells. Receptors were labelled with the lipophilic antagonists 3H-(+/-)-carazolol and 125I-(+/-)-cyanopindolol (CYP) or with the hydrophilic antagonist 3H-(+/-)-CGP 12177. Under equilibrium conditions all ligands bound to a saturable homogeneous class of specific sites with a maximal binding capacity of approximately 100 fmol/mg protein (corresponding to approximately 5000 sites/cell). After 90-180 min preincubation of intact cells with 3H-carazolol or 3H-CGP 12177 only 80% of these antagonists could be displaced from specific binding sites by competing ligands. In the simultaneous presence of the antagonist (-) timolol 100% of specifically bound radiolabelled ligand remained displaceable. In competitive displacement experiments the radioligands did not affect the apparent affinity of the displacing nonlabelled antagonists timolol and CGP 12177, but agonist affinity was markedly changed. The apparent KD values for (-)-isoprenaline were 1560 and 2720 nmol/l in the presence of carazolol and CYP, but only 32 nmol/l in the presence of CGP 12177. This antagonist-dependent difference in agonist KD values was observed o...Continue Reading

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Citations

Jan 1, 1988·In Vitro Cellular & Developmental Biology : Journal of the Tissue Culture Association·E LundgrenT K Borg
Apr 1, 1986·Pharmacology, Biochemistry, and Behavior·A De BlasiS Cotecchia
Oct 1, 2003·Clinical Positron Imaging : Official Journal of the Institute for Clinical P.E.T·P H ElsingaWillem Vaalburg
Aug 1, 1984·Proceedings of the National Academy of Sciences of the United States of America·S Kokubun, H Reuter
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Apr 16, 1985·Biochemical and Biophysical Research Communications·J S KarlinerW Woloszyn
Jun 7, 1996·The Journal of Biological Chemistry·F ShintaniT Nakaki
Sep 28, 2017·Scientific Reports·Gyuzel Y MitronovaStefan W Hell

Related Concepts

Carazolol, monohydrochloride
Cyclic AMP, (R)-Isomer
Novodrin
Ligands
Tissue Membrane
Myocardium
Propanolamines
Plasma Protein Binding Capacity
Norepinephrine Receptors
Beta-adrenergic receptor

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