L-type calcium channels regulate gastrin release from human antral G cells.
In mRNA samples isolated from a gastrin (G) cell-enriched human antral cell preparation, reverse transcription-polymerase chain reaction identified products encoding part of the alpha 1-subunit of class C and D L-type voltage-dependent Ca2+ channels (VDCCs). Analysis of the polymerase chain reaction products demonstrated a 100% homology with the known human gene sequences. An antibody to the class D alpha 1-subunit immunostained 30-40% of the cultured cells; of these 90% were gastrin immunoreactive. Gastrin release stimulated by terbutaline (beta 2-agonist) and forskolin was abolished by blockade of L-type VDCCs; the effect of 3.6 mM extracellular Ca2+ was only partially reversed. In G cells the rise in intracellular Ca2+ observed in response to increasing extracellular Ca2+ from 0.5 to 3.6 mM was reduced by nitrendipine. These results indicated that human antral cells expressed class C and D L-type VDCCs. Activation of G cells with beta-adrenergic agonists required an influx of extracellular Ca2+ through these channels to stimulate gastrin release. However, activation of L-type channels was not the only mechanism underlying Ca(2+)-stimulated gastrin release.
Ray
J M
JM
Department of Physiology, University of British Columbia, Vancouver, Canada.
Squires
P E
PE
Meloche
R M
RM
Nelson
D W
DW
Snutch
T P
TP
Buchan
A M
AM
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000328:Adult; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics / Q000502:physiology*; D005576:Colforsin / Q000494:pharmacology; D005260:Female; D005470:Fluorometry; D005755:Gastrins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008969:Molecular Sequence Data; D009568:Nitrendipine / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011706:Pyloric Antrum / Q000166:cytology / Q000378:metabolism*; D013726:Terbutaline / Q000494:pharmacology; D014158:Transcription, Genetic
D000318:Adrenergic beta-Agonists; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D005755:Gastrins; D005576:Colforsin; D009568:Nitrendipine; D013726:Terbutaline; D002118:Calcium