Involvement of intramuscular interstitial cells in nitrergic inhibition in the mouse gastric antrum

Abstract

Intracellular recordings were made from isolated bundles of the circular muscle layer of mouse gastric antrum and the responses evoked by stimulating intrinsic nerve fibres were examined. Transmural nerve stimulation evoked a fast inhibitory junction potential (fast‐IJP) which was followed initially by a smaller amplitude long lasting inhibitory junction potential (slow‐IJP) and a period of excitation. The excitatory component of the response was abolished by atropine, suggesting that it resulted from the release of acetylcholine and activation of muscarinic receptors. Fast‐IJPs were selectively reduced in amplitude by apamin and slow‐IJPs were abolished by Nω‐nitro‐l‐arginine. Slow‐IJPs were associated with a drop in membrane noise, suggesting that inhibition resulted from a reduced discharge of unitary potentials by intramuscular interstitial cells of Cajal (ICCIM). The chloride channel blocker, anthracene‐9‐carboxylic acid, reduced the discharge of membrane noise in a manner similar to that detected during the slow‐IJP. When recordings were made from the antrum of W/WV mice, which lack ICCIM, the cholinergic and nitrergic components were absent, with only fast‐IJPs being detected. The observations suggest that neurally released nitric oxide selectively targets ICCIM causing a hyperpolarization by suppressing the discharge of unitary potentials.

Immunohistochemical demonstration of c-Kit-negative fibroblast-like cells in murine gastrointestinal musculature

“…Apamin, the selective blocker of SK channels, has been shown to affect the mechanical and electrical activity of the GI musculature such as inhibitory junctional potential and relaxation induced by the inhibitory motor neurons (De Man et al, 2003;Suzuki et al, 2003). Therefore, apamin-sensitive SK channels are involved in the regulation of motility and electrical activity of the GI musculature.…”

The Significance of Interstitial Cells in Neurogastroenterology

“…ICC-IM have been suggested to be critical mediators of enteric neurotransmission [42][43][44][45][46] ; evidence for and against this will be discussed in later sections. ICC-IM also act as mechanosensitive regulators of pacemaker activity 47,48 and play a role in the guidance of vagal afferent nerves that form intramuscular arrays in the stomach.…”

“…For example, excitatory cholinergic stimulation increases STDs in the gastric antrum, and summation of these events can produce a positive chronotropic effect on slow wave generation. 45 …”

Changes in contractile and electrical activity in the ileum of DSS-induced colitis model W/Wv mutant mice

“…In the present study, however, the effects of L-NAME on circular and longitudinal smooth muscle contractions appeared to be similar, indicating enteric nitrergic inhibitory nerves (nNOS/NO) (Ward et al, 2000;Suzuki et al, 2003) and iNOS/NO (Aoi et al, 2008;Van Crombruggen et al, 2008) consequently modulate both circular and longitudinal smooth muscle contractions mediated via mechanisms as mentioned above (Liu et al, 1998).…”