title: Amperometric measurements of catecholamine release from single vesicles in MN9D cells.
abstract: MN9D cells have been used as a successful model to investigate dopamine pharmacology and to test the specific effects of drugs for the treatment of Parkinson's disease. However, quantitative measurements of quantal release from these cells have not been carried out. In this work, we used amperometry to investigate catecholamine release from MN9D cells. Amperometric events were observed in both undifferentiated and differentiated (butyric acid-treated) cells. An increase in quantal size and half-width was observed for differentiated cells versus undifferentiated cells; however, the number of events per cell and the amplitude remained constant. In transmission electron microscopy images, no obvious cluster of small synaptic vesicles was observed, and large dense-core vesicles were present in the cell body of undifferentiated cells; however, after differentiation, vesicles were concentrated in the cell processes. In differentiated cells, l-DOPA caused an increase in quantal size and half-width, which could be blocked by the vesicular monoamine transporter inhibitor, reserpine.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Dong
authors.forename: Michael L
authors.initials: ML
authors.lastname: Heien
authors.forename: Marc M
authors.initials: MM
authors.lastname: Maxson
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Ewing
mesh_terms: D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology; D000818:Animals; D002395:Catecholamines / Q000032:analysis*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002461:Cell Line, Transformed / Q000378:metabolism* / Q000648:ultrastructure; D015259:Dopamine Agents / Q000494:pharmacology; D055664:Electrochemical Techniques / Q000379:methods*; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D007980:Levodopa / Q000494:pharmacology; D051379:Mice; D046529:Microscopy, Electron, Transmission / Q000379:methods; D011189:Potassium Chloride / Q000494:pharmacology; D012110:Reserpine / Q000494:pharmacology; D022142:Secretory Vesicles / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D018759:Adrenergic Uptake Inhibitors; D002395:Catecholamines; D015259:Dopamine Agents; D007980:Levodopa; D011189:Potassium Chloride; D012110:Reserpine