title: Direct observation of membrane retrieval in chromaffin cells by capacitance measurements.
abstract: This study was focussed on the identification of the endocytic organelles in chromaffin cells which retrieve large, dense core vesicle (LDCV)-membrane components from the plasma membrane. For this purpose, 'on-cell' capacitance measurements and electron microscopy were employed. We found capacitance steps and capacitance flickers, corresponding to single exo- and endocytic events. The analysis revealed that the total membrane surface of completely fused LDCVs is recycled by large endocytic vesicles and smaller, most likely clathrin-coated vesicles, at approximately the same ratio. These results were confirmed by rapid-freeze immuno-electron microscopy, where an extracellular marker was rapidly internalized into endocytic vesicles that morphologically resembled LDCVs.
authors.affiliation: Department of Psychiatry (Molecular Neurobiology), University of Erlangen, Germany. andreas.henkel@psych.imed.uni-erlangen.de
authors.forename: A W
authors.initials: AW
authors.lastname: Henkel
authors.forename: H
authors.initials: H
authors.lastname: Horstmann
authors.forename: M K
authors.initials: MK
authors.lastname: Henkel
mesh_terms: D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000502:physiology / Q000648:ultrastructure*; D004705:Endocytosis; D008564:Membrane Potentials; D008854:Microscopy, Electron