ISSN:
1432-2013
Keywords:
Exocrine
;
Salivary
;
Cell line
;
Calcium
;
Muscarinic
;
Duct cell
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract We have studied receptor-mediated Ca2+ mobilization in an established exocrine epithelial cell line (HSG-PA) derived from a human submandibular gland. These cells possess a single class of high-affinity muscarinic cholinergic receptors identified using [3H]-quinuclidinylbezilate (K d=0.17±0.07 nmol/l;B max=37±2 fmol/mg protein;n=3). The muscarinic agonist carbachol elicits a concentration dependent increase of [3H]-inositol trisphosphate in HSG-PA cells (100 μmol/l; 〉2 fold by 30 s). Carbachol also results in a rapid, ∼5-fold increase in cytosolic [Ca2+]. This response is made up of two components, one arising from the release of intracellular Ca2+ (La3+ insensitive; independent of extracellular [Ca2+]), the other from the entry of extracellular Ca2+ (La3+ sensitive; dependent on extracellular [Ca2+]). These Ca2+ mobilizing mechanisms are completely blocked by the muscarinic antagonist atropine (10 μmol/l) but unaffected by several voltage-dependent Ca2+ channel antagonists (verapamil, nifedipine, diltiazem) and by membrane depolarization (incubation in 55 mmol/l KCl). These results demonstrate that HSG-PA cells respond to muscarinic stimulation by mobilizing Ca2+ from an intracellular store and via a receptor-operated Ca2+ entry pathway.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00594181
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