A1 Refereed original research article in a scientific journal
alpha(2B)-adrenoceptors couple to Ca2+ increase in both endogenous and recombinant expression systems
Authors: Holmberg CI, Kukkonen JP, Bischoff A, Nasman J, Courtney MJ, Michel MC, Akerman KEO
Publisher: ELSEVIER SCIENCE BV
Publication year: 1998
Journal: European Journal of Pharmacology
Journal name in source: EUROPEAN JOURNAL OF PHARMACOLOGY
Journal acronym: EUR J PHARMACOL
Volume: 363
Issue: 1
First page : 65
Last page: 74
Number of pages: 10
ISSN: 0014-2999
DOI: https://doi.org/https://doi.org/10.1016/S0014-2999(98)00780-8
The ability of cloned human alpha(2B)-adrenoceptors heterologously expressed in Sf9 cells and endogenous alpha(2B)-adrenoceptors in NG 108-15 neuroblastoma X glioma cells to couple to increase of intracellular Ca2+ was studied. Ca2+ increases in NG 108-15 cells were detectable but slight, whereas those in alpha(2B)-adrenoceptor-expressing Sf9 cells were greater. In the latter, the maximum Ca2+ increase correlated positively, and the EC50-value of noradrenaline negatively, with the receptor expression density. The order of potency of the agonists was D-medetomidine ([D]-4-[5]-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole) > noradrenaline approximate to clonidine > oxymetazoline, with clonidine and UK14,304 (5-bromo-N-[4,5-dihydro-1H-imidazole-2-yl]-6-quinoxalinamine) being weak partial agonists. In Sf9 cells Ca2+ increases consisted of concomitant mobilization from an intracellular store and influx of extracellular Ca2+. In these cells alpha(2B)-adrenoceptor stimulation also increased the inositol 1,4,5-trisphosphate mass. We conclude that alpha(2B)-adrenoceptors can couple to intracellular Ca2+ increases which may involve prior activation of phospholipase C. (C) 1998 Elsevier Science B.V. All rights reserved.
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