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Properties of the inhibitory junction potential in smooth muscle of the guinea‐pig gastric fundus
Author(s) -
Ohno Naotomo,
Xue Lin,
Yamamoto Yoshimichi,
Suzuki Hikaru
Publication year - 1996
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1996.tb15290.x
Subject(s) - apamin , hyperpolarization (physics) , suramin , tetrodotoxin , nitroarginine , vasoactive intestinal peptide , inhibitory postsynaptic potential , endocrinology , medicine , chemistry , biology , nitric oxide , potassium channel , nitric oxide synthase , neuropeptide , receptor , organic chemistry , nuclear magnetic resonance spectroscopy
1 In circular smooth muscle of the guinea‐pig gastric fundus, transmural nerve stimulation evoked a cholinergic excitatory junction potential (e.j.p.), and blockade of the e.j.p. by atropine revealed a non‐adreriergic non‐cholinergic (NANC) inhibitory junction potential (i.j.p.). 2 The amplitude of the e.j.p. was increased by apamin, suramin or N G nitro‐L‐arginine (L‐NOARG), with no significant change in the membrane potential. 3 The i.j.p. consisted of two components (fast and slow); apamin inhibited the former, nitroarginine inhibited the latter, and suramin inhibited both components. 4 Apamin inhibited the hyperpolarization produced by adenosine 5′‐triphosphate (ATP) but not by vasoactive intestinal polypeptide (VIP). Suramin inhibited the hyperpolarization produced by VIP but not by ATP. The sodium nitroprusside (SNP)‐induced hyperpolarization was not blocked by apamin or suramin. L‐NOARG or tetrodotoxin did not inhibit the hyperpolarization produced by ATP, VIP or SNP. 5 The data did not support the hypothesis that ATP, VIP or nitric oxide (NO) is the main transmitter responsible for generation of the NANC i.j.p. in the fundus. 6 Actions of L‐NOARG suggest that endogenous NO may be involved in junctional transmission, mainly as an inhibitory modulator of cholinergic transmission.