Open AccessCa 2+ participates in α 1B ‐adrenoceptor‐mediated cAMP response in HEK293 cells
Author(s) -
SONG Yao,
LI Yunfang,
DONG Erdan,
HAN Qide,
ZHANG Youyi
Publication year - 2005
Publication title -
acta pharmacologica sinica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.514
H-Index - 90
eISSN - 1745-7254
pISSN - 1671-4083
DOI - 10.1111/j.1745-7254.2005.00018.x
Subject(s) - hek 293 cells , adenylyl cyclase , pertussis toxin , egta , gi alpha subunit , chemistry , forskolin , agonist , gs alpha subunit , receptor , g protein , medicine , microbiology and biotechnology , endocrinology , biology , calcium , biochemistry , organic chemistry
Aim: To investigate the α 1B ‐adrenoceptor (α 1B ‐AR)‐mediated cAMP response and underlying mechanisms in HEK293 cells. Methods: Full‐length cDNA encoding α 1B ‐AR was transfected into HEK293 cells using the calcium phosphate precipitation method, and α 1B ‐AR expression and cAMP accumulation were determined by using the saturation radioligand binding assay and ion‐exchange chromatography, respectively. Results: Under agonist stimulation, α 1B ‐AR mediated cAMP synthesis in HEK293 cells, and blockade by PLC‐PKC or tyrosine kinase did not reduce cAMP accumulation induced by NE. Pretreatment with pertussis toxin (PTX) had little effect on basal cAMP accumulation as well as norepinephrine (NE)‐stimulated cAMP accumulation. In addition, pretreatment with cholera toxin (CTX) neither mimicked nor blocked the effect induced by NE. The extracellular Ca 2+ chelator egtazic acid (EGTA), nonselective Ca 2+ channel blocker CdCl 2 and calmodulin (CaM) inhibitor W‐7 significantly reduced NE‐induced cAMP accumulation from 1.59%±0.47% to 1.00%±0.31%, 0.78%±0.23%, and 0.90%±0.40%, respectively. Conclusion: By coupling with a PTX‐insensitive G protein, α 1B AR promotes Ca 2+ influx via receptor‐dependent Ca 2+ channels, then Ca 2+ is linked to CaM to form a Ca 2+ ‐CaM complex, which stimulates adenylyl cyclase (AC), thereby increasing the cAMP production in HEK293 cell lines.