Korean J Gastroenterol.  2003 May;41(5):358-365.

Nonadrenergic Noncholinergic Response in Fundic Strips of Guinea Pig Stomach and Its Modulation by Substance P

• Heo GS
• Chang SJ
• Park CG
• Kim MW
• Jang IY
• Kim JH
• Shin MK
• Yeum CH
• Yoon PJ
• Jun JY

Abstract

BACKGROUND/AIMS: In a gastric fundic strip, electrical field stimulation (EFS) evokes TTX-sensitive biphasic responses, consisting firstly of cholinergic contraction followed by a transient relaxation. It is well known that nonadrenergic noncholinergic (NANC) inhibitory nerve mediates a transient relaxation. This study was performed to investigate the characterization of relaxation and its modulation by substance P. METHODS: Using Guinea-pig gastric fundic smooth muscle tissues, we recorded mechanical contractions induced by EFS in the organ bath with platinum. RESULTS: N(G)-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthase, reduced EFS-induced relaxation and these effects were reversed by L-arginine, a precursor of nitric oxide (NO). Sodium nitroprusside, a NO-donor, suppressed the fundic basal tension. Cell permeable 8-bromo-cGMP inhibited noradrenaline-induced contraction. The application of substance P increased basal tension and EFS-induced contraction and relaxation. NK-1 receptor antagonist ([D-Pro9-(spiro--lactam)9,10-Trp11]-Substance P) inhibited substance P-induced effects. TEA and apamin, K+ channel blockers, increased basal tension and EFS-induced relaxation. CONCLUSIONS: These results indicate that NANC inhibitory responses are mainly mediated by NO in the guinea-pig fundus and the release of NO is modulated by substance P through NK-1 receptor and by prejunctional K+ channels.

Keyword

Nonadrenergic noncholinergic response; Nitric oxide; Substance P; Potassium channels