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R‐type Ca 2+ channels and inhibitory neuromuscular transmission in the gastrointestinal tract
Author(s) -
RodriguezTapia Eileen,
Galligan James
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1093.27
Subject(s) - inhibitory postsynaptic potential , neuromuscular transmission , purinergic receptor , nitric oxide , endocrinology , neurotransmission , guinea pig , medicine , stimulation , electrophysiology , chemistry , gastrointestinal tract , biophysics , biology , receptor , adenosine
Enteric inhibitory neuromuscular transmission relaxes gut smooth muscle via nitric oxide (NO) and purinergic mechanisms. In the guinea pig ileum, R‐type Ca 2+ channels couple to release of NO while P/Q‐ and N‐type Ca 2+ channels couple to release of the purine. In the current studies we tested the hypothesis that R‐type Ca 2+ channels also couple selectively to NO release in the mouse colon by studying relaxations and inhibitory junction potentials (IJPs). Methods Longitudinal muscle relaxations were studied using an in vitro organ bath system and intracellular recordings were conducted to study IJPs. Both responses were evoked using electrical field stimulation. The effects of drugs applied to the organ bath solution were investigated. Results The R‐type Ca 2+ channel blocker, NiCl 2 (1–50 micromolar) did not alter neurogenic relaxation (10 Hz, 1s stimulus train) of the mouse distal colon. However, NiCl 2 (50 micromolar) reduced the peak response and integrated areal of the IJP (1–60 Hz, 200 ms stimulus train). Conclusion R‐type Ca 2+ channels couple to release of inhibitory neurotransmitters in the guinea pig and mouse gastrointestinal tract. The relationship between IJPs and relaxation of the mouse colon is not clear.