Intracellular signal transduction pathways of muscarinic-induced
mucin secretion by primary cultures of hamster tracheal goblet
cells.
Steel, Daniella M., and John. W. Hanrahan.
Department of Physiology and Respiratory Health Network of Centres
of Excellence, McGill University, Montr[acute]eal, Qu[acute]ebec,
Canada, H3G 1Y6
APStracts 3:0173L, 1996.
Hamster tracheal epithelial cell cultures were used to investigate
muscarinic regulation of high-molecular-weight glycoconjugate (HMWG)
secretion by airway goblet cells. HMWG were radiolabeled with N
-acetyl-D-[1-3H]glucosamine, precipitated with trichloroacetic acid
and phosphotungstic acid, and counted by liquid scintillation.
Carbachol (100 [mu]M) increased HMWG secretion (166.6+/-18.7%,
p<0.001, n=20), and this response was blocked by the
muscarinic receptor antagonist atropine. Ca2+ may not be essential
for the carbachol response since: i) carbachol-activated secretion
was not inhibited by chelating extracellular Ca2+ with BAPTA, nor by
reducing both extracellular and intracellular Ca2+ with BAPTA-AM in
low-Ca2+ medium; ii) the carbachol response was only partially
blocked in low-Ca2+ medium; iii) calcium ionophore did not stimulate
HMWG secretion. However, carbachol-stimulated secretion was abolished
by pertussis toxin (PTX), indicating the involvement of a PTX
-sensitive G-protein, and by the protein kinase C (PKC) inhibitor
chelerythrine chloride. Furthermore, carbachol-stimulated secretion
was not inhibited by overnight incubation with the phorbol ester PMA.
In conclusion, carbachol-stimulated secretion of HMWG appears to be
coupled to a PTX-sensitive G-protein and requires the activation of a
phorbol-ester-insensitive PKC isoform.
Received 3 July 1996; accepted in final form 18 September 1996.
APS Manuscript Number L203-6.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996