alpha(2B)-adrenoceptors couple to Ca2+ increase in both endogenous and recombinant expression systems
Courtney MJ; Michel MC; Akerman KEO; Holmberg CI; Kukkonen JP; Bischoff A; Nasman J
alpha(2B)-adrenoceptors couple to Ca2+ increase in both endogenous and recombinant expression systems
Courtney MJ
Michel MC
Akerman KEO
Holmberg CI
Kukkonen JP
Bischoff A
Nasman J
ELSEVIER SCIENCE BV
Julkaisun pysyvä osoite on:
https://urn.fi/URN:NBN:fi-fe2021042716377
https://urn.fi/URN:NBN:fi-fe2021042716377
Tiivistelmä
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.
Kokoelmat
- Rinnakkaistallenteet [19207]