title: 4-Aminopyridine induces the release of neuropeptide Y (NPY) to produce an atropine- and tetrodotoxin-resistant contraction in rabbit isolated jejunum.
abstract: 4-Aminopyridine (4-AP) induced an atropine- and tetrodotoxin (TTX)-insensitive contraction (resistant contraction), in a concentration-dependent manner, in the isolated jejunum of rabbits. The failure of specific antagonists of histamine, serotonin and substance P to affect this resistant contraction ruled out the participation of histamine, serotonin and/or substance P. Antiserum against neuropeptide Y (NPY) reduced this resistant contraction in a concentration-dependent manner and inhibited the action of 4-AP totally at a high concentration (1.25% dilution) whereas normal serum lacked this ability. This suggested that the release of NPY was involved in this 4-AP-induced resistant contraction. Radioimmunoassay of NPY-like immunoreactivity in isolated synaptosomal preparations indicated that 4-AP possessed the ability to induce the release of NPY. However, guanethidine did not affect the actions of 4-AP, indicating that NPY is released mainly from non-adrenergic nerves. Our results indicate that 4-AP induces the release of NPY from non-adrenergic nerves to produce an atropine- and TTX-resistant contraction in the isolated jejunum of rabbits.
authors.affiliation: Department of Pharmacology, College of Medicine, National Cheng Kung University, Taiwan, Republic of China.
authors.forename: J T
authors.initials: JT
authors.lastname: Cheng
authors.forename: S Y
authors.initials: SY
authors.lastname: Hsu
authors.forename: C L
authors.initials: CL
authors.lastname: Shen
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D004351:Drug Resistance; D005260:Female; D066298:In Vitro Techniques; D007583:Jejunum / Q000187:drug effects / Q000201:enzymology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000201:enzymology; D009478:Neuropeptide Y / Q000378:metabolism* / Q000502:physiology; D011817:Rabbits; D011863:Radioimmunoassay; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology*
chemical_list: D009478:Neuropeptide Y; D013779:Tetrodotoxin; D001285:Atropine; D015761:4-Aminopyridine; D007770:L-Lactate Dehydrogenase