Acetylcholine induces cytosolic Ca2+ mobilization in isolated distal colonic crypts from normal and cystic fibrosis mice.
In intestinal biopsies from cystic fibrosis (CF) patients acetylcholine fails to elicit a chloride secretion response, and this observation can be explained by a defect in the Ca2+ signalling pathway in CF secretory cells. We tested the hypothesis that in CF intestine, the generation of an intracellular Ca2+ signal upon cholinergic stimulation is absent. A transgenic CF mouse model was used. Electrical measurements on intact jejunum and unstripped colon were performed in Ussing chambers. Intact distal colonic crypts were isolated, and the intracellular Ca2+ concentration was monitored using the Ca2+-sensitive dye fura-2. Acetylcholine increased the short-circuit current generated by wild-type jejunum and colon, but failed to induce a response in CF tissues. Acetylcholine caused a transient elevation in the intracellular Ca2+ concentration in colonic crypts from both wild-type and CF mice; the amplitude and timing of the response in CF crypts was indistinguishable from that in wild-type crypts. The response to acetylcholine was also observed in the absence of extracellular calcium, indicating intracellular stores as the source from which the cytosolic Ca2+ concentration increased. We conclude that the absence of a cholinergically-induced secretory response in CF intestine is not due to a defect in the generation of a Ca2+ signal in intestinal cells upon cholinergic stimulation.
Klaren
P H
PH
Department of Biomedical Science, University of Sheffield, UK.
Hardcastle
J
J
Evans
S
S
Colledge
W H
WH
Evans
M J
MJ
Taylor
C J
CJ
Hardcastle
P T
PT
White
S J
SJ
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004594:Electrophysiology; D005456:Fluorescent Dyes; D005470:Fluorometry; D016257:Fura-2; D051379:Mice; D008822:Mice, Transgenic; D010641:Phenotype
D005456:Fluorescent Dyes; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2