title: Selective depletion of the acetylcholine and vasoactive intestinal polypeptide of the guinea-pig myenteric plexus by differential mobilization of distinct transmitter pools.
abstract: The effect of electrical field stimulation on the release of acetylcholine (ACh) and vasoactive intestinal polypeptide (VIP) from superfused strips of myenteric plexus-longitudinal muscle (MPLM) of guinea-pig ileum and on the transmitter content of the tissue was investigated at different frequencies and in the presence and absence of choline hemicholinium-3 and colchicine. Low frequency electrical field stimulation released ACh by more than 4 times the basal release; the simultaneously detected VIP secretion was increased only slightly above the resting level. During high frequency stimulation (50 Hz) the release of VIP was greatly increased (to 5 times the resting release) whereas the release of ACh increased to only 150% of the basal output. When choline was present, the ACh content of the tissue itself was not altered by electrical stimulation indicating a rate of synthesis sufficient to maintain release. It was reduced in a frequency-dependent manner in the absence of exogenous choline or in the presence of 10 microM hemicholinium-3 (an inhibitor of choline uptake) by up to 54% of the original content. A similar but even larger reduction took place in the amount of ACh released. Neither the secretion of VIP nor the tissue VIP content was altered by these treatments. Long-lasting (greater than 60 min) high-frequency (50 Hz) stimulation resulted in the depletion of the VIP pool (by 25%) while the ACh content remained unaltered.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Abteilung Neurochemie, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Federal Republic of Germany.
authors.forename: D V
authors.initials: DV
authors.lastname: Agoston
authors.forename: J M
authors.initials: JM
authors.lastname: Conlon
authors.forename: V P
authors.initials: VP
authors.lastname: Whittaker
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003078:Colchicine / Q000494:pharmacology; D004558:Electric Stimulation; D006168:Guinea Pigs; D006426:Hemicholinium 3 / Q000494:pharmacology; D007082:Ileum / Q000294:innervation; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D009197:Myenteric Plexus / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D012016:Reference Values; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism*; D014701:Veratridine / Q000494:pharmacology
chemical_list: D006426:Hemicholinium 3; D014660:Vasoactive Intestinal Peptide; D014701:Veratridine; D008274:Magnesium; D000109:Acetylcholine; D011188:Potassium; D003078:Colchicine; D002118:Calcium