title: Radioactive choline metabolism in guinea pig gallbladder. Is there measurable acetylcholine release?
abstract: Acetylcholine may be released from gallbladder intrinsic nerves in response to cholecystokinin stimulation. This study characterized metabolites of [14C]choline produced in the gallbladder and released during incubation, with or without cholecystokinin-octapeptide. Radiolabeled [14C]choline was applied to the mucosal or muscle surface of intact guinea pig gallbladders in an organ bath. After radiolabeling, gallbladders were incubated with or without the contractile agonist cholecystokinin-octapeptide. Metabolites of [14C]choline were identified in gallbladder tissue and incubation buffers using HPLC and thin-layer chromatography. The major metabolites of [14C]choline were betaine and phosphocholine. [14C]Phosphocholine was incorporated slowly into [14C]phosphatidylcholine. [14C]Choline was released into buffers during incubation. [14C]Acetylcholine constituted less than 1% of radiolabel in the gallbladder. There was no identifiable [14C]acetylcholine released in buffers. Cholecystokinin-octapeptide did not affect choline metabolism. These studies showed that choline in the gallbladder is metabolized along pathways similar to those in the liver. Gallbladders released mostly choline, rather than acetylcholine, even during hormonally induced contraction.
authors.affiliation: Department of Surgery, Boston University School of Medicine, Massachusetts, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Brotschi
authors.forename: C L
authors.initials: CL
authors.lastname: Hilbinger
authors.forename: E A
authors.initials: EA
authors.lastname: Kahl
authors.forename: W A
authors.initials: WA
authors.lastname: Vaules
authors.forename: N A
authors.initials: NA
authors.lastname: Midis
authors.forename: J K
authors.initials: JK
authors.lastname: Blusztajn
authors.forename: S H
authors.initials: SH
authors.lastname: Zeisel
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001622:Betaine / Q000378:metabolism; D002250:Carbon Radioisotopes; D002794:Choline / Q000378:metabolism*; D005260:Female; D005704:Gallbladder / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D006168:Guinea Pigs; D010767:Phosphorylcholine / Q000378:metabolism; D012844:Sincalide / Q000494:pharmacology; D013997:Time Factors
chemical_list: D002250:Carbon Radioisotopes; D010767:Phosphorylcholine; D001622:Betaine; D012844:Sincalide; D002794:Choline; D000109:Acetylcholine