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  • 1
    ISSN: 1573-6903
    Keywords: Synaptosome subpopulations ; coexistence ; co-release ; amino acids ; cholecystokinin ; vasoactive intestinal peptide ; somatostatin ; acetylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract GABAergic and cholinergic synaptosome populations were isolated by immunomagnetophoresis. Analysis of 8 amino acids showed that the GABAergic population was enriched in GABA (3 fold). The cholinergic population was enriched in citrulline (5 fold). CCK was found in both populations, but was enriched in the GABAergic. No monoamines were found in either subpopulation. Stimulated release (veratridine 50 μm), measured using a superfusion system, showed that glutamate was only released from the cholinergic subpopulation, as was VIP. In the GABAergic population, stimulated SRIF release was slow and prolonged, and the CCK release was delayed and rapid. GABA release was rapid, only occurring during application of the stimulus and only from the GABAergic synaptosomes. The GABAergic release could be modified by GABAA and GABAB targeted drugs. The cholinergic subpopulation exhibited late release of both VIP and CCK, each showing the same time pattern of release. All release was calcium and tetrodotoxin dependent.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2568
    Keywords: colon ; colonic polyps ; vasoactive intestinal peptide ; somatostatin ; enteroglucagon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The study was undertaken to examine regional differences in the concentrations of five regulatory peptides in the human colonic mucosa. Biopsies were obtained during routine colonoscopy from 33 patients whose colonic mucosa was macroscopically and histologically normal. Regulatory peptides were extracted, and measured by specific radioimmunoassays. Concentrations of three peptides that are present predominantly in endocrine cells within colonic mucosa increased significantly towards the rectum: Mean concentrations of peptide YY, enteroglucagon, and somatostatin were about three times greater in the rectum than in the cecum. However, concentrations of two peptides that are present in mucosal nerve fibers diminished significantly towards the rectum: Mean rectal concentrations of vasoactive intestinal peptide and peptide histidine methionine were both about 0.6 of mean cecal concentrations. Concentrations of all five peptides were lower in biopsies taken from colonic polyps than in normal colonic mucosa. Regional differences in colonic mucosal concentrations of regulatory peptides probably reflect differences in the physiological functions of different parts of the colon.
    Type of Medium: Electronic Resource
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