title: VMAT-Mediated changes in quantal size and vesicular volume.
abstract: It has been well established that the volume of secretory vesicles can be modulated. However, we present the first data demonstrating that the amount of transmitter in a vesicle can regulate its volume. Amperometry and transmission electron microscopy have been used to determine that l-3,4-dihydroxyphenylalanine and reserpine increase and decrease, respectively, the volume of single pheochromocytoma cell vesicles as well as their catecholamine content. Because changes in vesicular catecholamine content are tracked by changes in vesicle volume, our results indicate that when quantal size is altered via the vesicular monoamine transporter the concentration of catecholamines within the vesicles remains relatively constant. This previously unidentified cellular response provides new insight into how catecholamines can be packaged in and released from secretory vesicles.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: T L
authors.initials: TL
authors.lastname: Colliver
authors.forename: S J
authors.initials: SJ
authors.lastname: Pyott
authors.forename: M
authors.initials: M
authors.lastname: Achalabun
authors.forename: A G
authors.initials: AG
authors.lastname: Ewing
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology; D000818:Animals; D002395:Catecholamines / Q000096:biosynthesis / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D004295:Dihydroxyphenylalanine / Q000494:pharmacology; D015259:Dopamine Agents / Q000494:pharmacology; D004563:Electrochemistry; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008854:Microscopy, Electron; D009479:Neuropeptides; D015388:Organelles / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D016716:PC12 Cells; D051381:Rats; D012110:Reserpine / Q000494:pharmacology; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins
chemical_list: D018759:Adrenergic Uptake Inhibitors; D002395:Catecholamines; D015259:Dopamine Agents; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009479:Neuropeptides; D050492:Vesicular Biogenic Amine Transport Proteins; D050493:Vesicular Monoamine Transport Proteins; D004295:Dihydroxyphenylalanine; D012110:Reserpine