title: Long term stimulation changes the vesicular monoamine transporter content of chromaffin granules.
abstract: Bovine chromaffin cells cultured for 5 days in the presence of depolarizing concentrations of K+ ions show a decreased number of secretory (chromaffin) granules per cell. These cells were still capable of exocytosis. Their contents in catecholamine and chromogranin A, components of the granule matrix, and cytochrome b561, a major protein of the granule membrane, were decreased to 35, 30, and 50% of control cells, respectively. However, in the same cells, the number of [3H]dihydrotetrabenazine binding sites, a specific ligand of the vesicular monoamine transporter, was increased to 180% of controls. In situ uptake of noradrenaline in permeabilized cells indicated that [3H]dihydrotetrabenazine binding sites were associated with a functional vesicular monoamine transporter. When analyzed by isopycnic centrifugation, these sites cosedimented with catecholamine, chromogranin A, and cytochrome b561, in a peak with a density lighter than that from controls. The composition of this peak suggests that it contains incompletely matured secretory granules, with a 3-5-fold increase in the vesicular monoamine transporter content of this membrane. This increase might indicate that an adaptative process occurs which allows a faster filling of the granules in continuously secreting cells.
authors.affiliation: Centre National de la Recherche Scientifique, Unité Associée 1112, Institut de Biologie Physico-Chimique, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Desnos
authors.forename: M P
authors.initials: MP
authors.lastname: Laran
authors.forename: K
authors.initials: K
authors.lastname: Langley
authors.forename: D
authors.initials: D
authors.lastname: Aunis
authors.forename: J P
authors.initials: JP
authors.lastname: Henry
mesh_terms: D000818:Animals; D001692:Biological Transport; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002458:Cell Fractionation; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D002837:Chromaffin Granules / Q000378:metabolism*; D002838:Chromaffin System / Q000166:cytology / Q000648:ultrastructure; D053379:Chromogranin A; D002864:Chromogranins / Q000302:isolation & purification; D003573:Cytochrome b Group / Q000032:analysis; D005089:Exocytosis; D005455:Fluorescent Antibody Technique; D006023:Glycoproteins / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009479:Neuropeptides; D009638:Norepinephrine / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D013268:Stimulation, Chemical; D013747:Tetrabenazine / Q000031:analogs & derivatives / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000302:isolation & purification; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins
chemical_list: D002395:Catecholamines; D053379:Chromogranin A; D002864:Chromogranins; D003573:Cytochrome b Group; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009479:Neuropeptides; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins; C023646:cytochrome b561; C032811:dihydrotetrabenazine; D014446:Tyrosine 3-Monooxygenase; D011188:Potassium; D009638:Norepinephrine; D013747:Tetrabenazine