Ryanodine receptor subtype 2 encodes Ca2+ oscillations activated by acetylcholine via the M2 muscarinic receptor/cADP-ribose signalling pathway in duodenum myocytes

N. Fritz
Journal of Cell Science. 2005-05-15; 118(10): 2261-2270
DOI: 10.1242/jcs.02344

PubMed
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1. J Cell Sci. 2005 May 15;118(Pt 10):2261-70. Epub 2005 May 3.

Ryanodine receptor subtype 2 encodes Ca2+ oscillations activated by acetylcholine
via the M2 muscarinic receptor/cADP-ribose signalling pathway in duodenum
myocytes.

Fritz N(1), Macrez N, Mironneau J, Jeyakumar LH, Fleischer S, Morel JL.

Author information:
(1)Laboratoire de Signalisation et Interactions Cellulaires, CNRS UMR 5017,
Université Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.

In this study, we characterized the signalling pathway activated by acetylcholine
that encodes Ca2+ oscillations in rat duodenum myocytes. These oscillations were
observed in intact myocytes after removal of external Ca2+, in permeabilized
cells after abolition of the membrane potential and in the presence of heparin
(an inhibitor of inositol 1,4,5-trisphosphate receptors) but were inhibited by
ryanodine, indicating that they are dependent on Ca2+ release from intracellular
stores through ryanodine receptors. Ca2+ oscillations were selectively inhibited
by methoctramine (a M2 muscarinic receptor antagonist). The M2 muscarinic
receptor-activated Ca2+ oscillations were inhibited by 8-bromo cyclic adenosine
diphosphoribose and inhibitors of adenosine diphosphoribosyl cyclase (ZnCl2 and
anti-CD38 antibody). Stimulation of ADP-ribosyl cyclase activity by acetylcholine
was evaluated in permeabilized cells by measuring the production of cyclic
guanosine diphosphoribose (a fluorescent compound), which resulted from the
cyclization of nicotinamide guanine dinucleotide. As duodenum myocytes expressed
the three subtypes of ryanodine receptors, an antisense strategy revealed that
the ryanodine receptor subtype 2 alone was required to initiate the Ca2+
oscillations induced by acetylcholine and also by cyclic adenosine
diphosphoribose and rapamycin (a compound that induced uncoupling between 12/12.6
kDa FK506-binding proteins and ryanodine receptors). Inhibition of cyclic
adenosine diphosphoribose-induced Ca2+ oscillations, after rapamycin treatment,
confirmed that both compounds interacted with the ryanodine receptor subtype 2.
Our findings show for the first time that the M2 muscarinic receptor activation
triggered Ca2+ oscillations in duodenum myocytes by activation of the cyclic
adenosine diphosphoribose/FK506-binding protein/ryanodine receptor subtype 2
signalling pathway.

DOI: 10.1242/jcs.02344
PMID: 15870112 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus