A1 adenosine receptors expressed in CHO-cells couple to adenylyl cyclase and to phospholipase C

  • Sebastian Freund
  • Martin Ungerer
  • Martin J. Lohse
Article

DOI: 10.1007/BF00180010

Cite this article as:
Freund, S., Ungerer, M. & Lohse, M.J. Naunyn-Schmiedeberg's Arch Pharmacol (1994) 350: 49. doi:10.1007/BF00180010

Abstract

A1 adenosine receptors are in general coupled to inhibition of adenylyl cyclase, but have more recently been reported to be capable of also activating phospholipase C. The present study was done in order to investigate whether these different effects can be elicited by a single A1 receptor, or whether A1 receptor subtypes have to be invoked. The cDNA of a rat brain A1 adenosine receptor was stably expressed in CHO-cells, resulting in clones with varying receptor densities; a clone expressing 1.9 pmol receptors/mg membrane protein was used for further characterization. The ligand binding properties of the expressed receptors were typical for the rat A1 adenosine receptor. A1 receptor agonists caused a concentration-dependent inhibition of adenylyl cyclase activity in the membranes, with maximal inhibition by 70%. A1 receptor stimulation also caused concentration-dependent stimulation of inositol phosphate generation in these cells, with maximal effects of 300%. Both adenylyl cyclase inhibition and enhancement of inositol phosphate generation were essentially abolished after pretreatment of the cells with pertussis toxin. These results indicate that a single A1 adenosine receptor can couple to two effector pathways, and that both effectors are activated via pertussis toxin sensitive G proteins.

Key words

A1 adenosine receptor Receptor expression Adenylyl cyclase Phospholipase C 

Abbreviations

CHA

N6-cyclohexyladenosine

CPA

N6-cyclopentyladenosine

DPCPX

8-cyclopentyl-1,3-dipropylxanthine

NECA

5′-N-ethylcarboxamidoadenosine

R-PIA

R-N6-phenylisopropyladenosine

IP1

inositol monophosphates

IP2

inositol bisphosphates

IP3

inositol trisphosphates

PCR

polymerase chain reaction

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Sebastian Freund
    • 1
    • 2
  • Martin Ungerer
    • 1
    • 2
  • Martin J. Lohse
    • 1
    • 2
  1. 1.Laboratorium für molekulare Biologic der Universitat MünchenMartinsriedGermany
  2. 2.Institut für Pharmakologie und Toxikologic der Universität WürzburgWürzburgGermany

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