title: Development of vagal innervation to the muscle of the avian gizzard.
abstract: The development of the vagal innervation to the gizzard has been investigated in chick embryos and young chicks. The membrane potential, first measurable on the 15th day of incubation, was -54 +/- 0.5 mV and increased with development to -67 +/- 0.4 mV. The latter value was attained 5 days after hatching and persisted thereafter. Stimulation of intramural nerves elicited a cholinergic, excitatory junction potential (EJP) for the first time, only in a small fraction of cells, on the 20th day of incubation. Within 3 days after hatching, cholinergic transmission showed the same features as in older chicks. Stimulation of the vagus nerve elicited no membrane potential responses before hatching but as early as 4 days after hatching, non-adrenergic, inhibitory junction potentials (IJPs) were evoked. In the next 10 days or so, the IJP was replaced with a cholinergic EJP as seen in mature tissues. After atropine (0.1-1 microM) treatment, both vagal and intramural nerve stimulation evoked a non-adrenergic IJP in a small fraction of cells immediately after hatching. The fraction of cells exhibiting the IJP increased with growth and reached 100% 5 days after hatching. Hexamethonium (50 or 100 microM) abolished the vagally-evoked EJPs. The vagally-evoked IJPs remained unchanged after application of hexamethonium in the early days after hatching, but later they were abolished in about half of the cells.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Veterinary Science, Faculty of Agriculture, Gifu University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohashi
authors.forename: T
authors.initials: T
authors.lastname: Takewaki
authors.forename: T
authors.initials: T
authors.lastname: Unno
authors.forename: S
authors.initials: S
authors.lastname: Komori
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000375:Aging / Q000502:physiology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002642:Chick Embryo; D002645:Chickens; D004558:Electric Stimulation; D005895:Gizzard, Avian / Q000187:drug effects / Q000254:growth & development* / Q000294:innervation; D006584:Hexamethonium Compounds / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008839:Microelectrodes; D024510:Muscle Development; D009130:Muscle, Smooth / Q000187:drug effects / Q000254:growth & development* / Q000294:innervation; D009469:Neuromuscular Junction / Q000502:physiology; D014630:Vagus Nerve / Q000187:drug effects / Q000254:growth & development*
chemical_list: D006584:Hexamethonium Compounds; D001285:Atropine; D000109:Acetylcholine