title: Colocalization of calcium entry and exocytotic release sites in adrenal chromaffin cells.
abstract: "Snapshot" images of localized Ca2+ influx into patch-clamped chromaffin cells were captured by using a recently developed pulsed-laser imaging system. Transient opening of voltage-sensitive Ca2+ channels gave rise to localized elevations of Ca2+ that had the appearance of either "hotspots" or partial rings found immediately beneath the plasma membrane. When the Ca2+ imaging technique was employed in conjunction with flame-etched carbon-fiber electrodes to spatially map the release sites of catecholamines, it was observed that the sites of Ca2+ entry and catecholamine release were colocalized. These results provide functional support for the idea that secretion occurs from "active zone"-like structures in neuroendocrine cells.
authors.affiliation: Department of Physiology and Biophysics, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: I M
authors.initials: IM
authors.lastname: Robinson
authors.forename: J M
authors.initials: JM
authors.lastname: Finnegan
authors.forename: J R
authors.initials: JR
authors.lastname: Monck
authors.forename: R M
authors.initials: RM
authors.lastname: Wightman
authors.forename: J M
authors.initials: JM
authors.lastname: Fernandez
mesh_terms: D000313:Adrenal Medulla / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D004594:Electrophysiology / Q000379:methods; D005089:Exocytosis; D013050:Spectrometry, Fluorescence
chemical_list: D002395:Catecholamines; D002118:Calcium