Ca(2+) signaling in porcine duodenal glands by muscarinic receptor activation.
The duodenal glands have been thought to play an important role in defense against proximal duodenal ulcer; however, the secretory mechanisms of these glands remain to be determined. In isolated duodenal acinar cells of the pig, we investigated the effects of ACh on intracellular Ca(2+) concentration ([Ca(2+)](i)) and on membrane currents with fura 2 fluorometry and the patch clamp technique. ACh caused a transient increase in [Ca(2+)](i), and the increase was markedly inhibited by atropine or 4-diphenylacetoxy-N-methylpiperidine methiodide but not by hexamethonium, pirenzepine, or methoctramine. The expression of mRNA for the M(3) subtype far exceeded that for either M(1) or M(2) as revealed by real-time quantitative PCR and in situ hybridization. The rise in [Ca(2+)](i) evoked by ACh was largely inhibited by thapsigargin but slightly affected by extracellular Ca(2+) deprivation. Caffeine had no effect on [Ca(2+)](i). ACh elicited Ca(2+)-dependent K(+) currents, a finding similar to the response to inositol 1,4,5,-trisphosphate applied intracellularly. These results suggest the presence of M(3) receptors linked to Ca(2+) release in porcine duodenal glands.
Department of Toxicology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501, Japan. hteraoka@rakuno.ac.jp
H
H
Teraoka
Y
Y
Maruyama
K
K
Takehana
T
T
Iwanaga
T
T
Hiraga
S
S
Fujita
T
T
Ohta
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000818:Animals; D002118:Calcium / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D004386:Duodenum / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005088:Exocrine Glands / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D012313:RNA; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D019284:Thapsigargin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; C034477:RNA primers; D011976:Receptors, Muscarinic; D012313:RNA; D019284:Thapsigargin; D000251:Adenosine Triphosphatases; D002118:Calcium