Control of intracellular Ca2+ by adrenergic and muscarinic agonists in mouse mandibular ducts and end-pieces.
The changes in free Ca2+ ([Ca2+]i) in the cells of the secretory end-pieces and intralobular ducts of mouse mandibular glands exposed to adrenergic or cholinergic agonists were measured using fluorescence imaging techniques. [Ca2+]i in both cell types increased in a dose-dependent manner during both adrenergic and cholinergic stimulation. The duct cells responded to noradrenaline and to acetylcholine over the same concentration range (30 nmol/l to 3 mumol/l) although the maximum increase in [Ca2+]i above resting levels evoked by noradrenaline (ca. 137 nmol/l) was about twice that evoked by acetylcholine. The response to acetylcholine was blocked by atropine (0.1 mumol/l) and the response to noradrenaline was blocked by the alpha 1-adrenergic antagonist, prazosin (0.1 mumol/l), but not by the alpha 2-adrenergic antagonist, yohimbine. The alpha-adrenergic agonist, phenylephrine, mimicked the action of noradrenaline but the beta-adrenergic agonist, isoproterenol, had no effect. In contrast to the duct cells, the end-piece cells responded to acetylcholine at much lower concentrations (threshold << 1 nmol/l) than to noradrenaline (threshold ca. 300 nmol/l) and the size of the increase in [Ca2+]i above resting levels evoked by acetylcholine (216 nmol/l) was nearly 5-times greater than for noradrenaline. VIP and substance P failed to evoked a Ca2+ response in either end-piece or duct cells.
Dinudom
A
A
Department of Physiology, University of Sydney, NSW, Australia.
Poronnik
P
P
Allen
D G
DG
Young
J A
JA
Cook
D I
DI
D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D008297:Male; D051379:Mice; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D012469:Salivary Glands / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D010656:Phenylephrine; D000109:Acetylcholine; D002118:Calcium; D009638:Norepinephrine; D011224:Prazosin