title: Dynasore inhibits rapid endocytosis in bovine chromaffin cells.
abstract: Vesicle recycling is vital for maintaining membrane homeostasis and neurotransmitter release. Multiple pathways for retrieving vesicles fused to the plasma membrane have been reported in neuroendocrine cells. Dynasore, a dynamin GTPase inhibitor, has been shown to specifically inhibit endocytosis and vesicle recycling in nerve terminals. To characterize its effects in modulating vesicle recycling and repetitive exocytosis, changes in the whole cell membrane capacitance of bovine chromaffin cells were recorded in the perforated-patch configuration. Constitutive endocytosis was blocked by dynasore treatment, as shown by an increase in membrane capacitance. The membrane capacitance was increased during strong depolarizations and declined within 30 s to a value lower than the prestimulus level. The amplitude, but not the time constant, of the rapid exponential decay was significantly decreased by dynasore treatment. Although the maximal increase in capacitance induced by stimulation was significantly increased by dynasore treatment, the intercepts at time 0 of the curve fitted to the decay phase were all approximately 110% of the membrane capacitance before stimulation, regardless of the dynasore concentration used. Membrane depolarization caused clathrin aggregation and F-actin continuity disruption at the cell boundary, whereas dynasore treatment induced clathrin aggregation without affecting F-actin continuity. The number of invagination pits on the surface of the plasma membrane determined using atomic force microscopy was increased and the pore was wider in dynasore-treated cells. Our data indicate that dynamin-mediated endocytosis is the main pathway responsible for rapid compensatory endocytosis.
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan.
authors.forename: Chia-Chang
authors.initials: CC
authors.lastname: Tsai
authors.forename: Chih-Lung
authors.initials: CL
authors.lastname: Lin
authors.forename: Tzu-Lun
authors.initials: TL
authors.lastname: Wang
authors.forename: Ai-Chuan
authors.initials: AC
authors.lastname: Chou
authors.forename: Min-Yi
authors.initials: MY
authors.lastname: Chou
authors.forename: Chia-Hsueh
authors.initials: CH
authors.lastname: Lee
authors.forename: I-Wei
authors.initials: IW
authors.lastname: Peng
authors.forename: Jia-Hong
authors.initials: JH
authors.lastname: Liao
authors.forename: Yit-Tsong
authors.initials: YT
authors.lastname: Chen
authors.forename: Chien-Yuan
authors.initials: CY
authors.lastname: Pan
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D019439:Chromaffin Cells / Q000187:drug effects / Q000502:physiology; D002966:Clathrin / Q000378:metabolism; D025802:Electric Capacitance; D004705:Endocytosis / Q000187:drug effects*; D005089:Exocytosis / Q000502:physiology; D005456:Fluorescent Dyes / Q000378:metabolism; D006835:Hydrazones / Q000494:pharmacology*; D018625:Microscopy, Atomic Force; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D011726:Pyridinium Compounds / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D022161:Transport Vesicles / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D002966:Clathrin; C092350:FM 4-64; D005456:Fluorescent Dyes; D006835:Hydrazones; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D011188:Potassium; D002118:Calcium