title: F-actin and myosin II accelerate catecholamine release from chromaffin granules.
abstract: The roles of nonmuscle myosin II and cortical actin filaments in chromaffin granule exocytosis were studied by confocal fluorescence microscopy, amperometry, and cell-attached capacitance measurements. Fluorescence imaging indicated decreased mobility of granules near the plasma membrane following inhibition of myosin II function with blebbistatin. Slower fusion pore expansion rates and longer fusion pore lifetimes were observed after inhibition of actin polymerization using cytochalasin D. Amperometric recordings revealed increased amperometric spike half-widths without change in quantal size after either myosin II inhibition or actin disruption. These results suggest that actin and myosin II facilitate release from individual chromaffin granules by accelerating dissociation of catecholamines from the intragranular matrix possibly through generation of mechanical forces.
authors.affiliation: School of Applied and Engineering Physics, and Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Khajak
authors.initials: K
authors.lastname: Berberian
authors.forename: Alexis J
authors.initials: AJ
authors.lastname: Torres
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Fang
authors.forename: Kassandra
authors.initials: K
authors.lastname: Kisler
authors.forename: Manfred
authors.initials: M
authors.lastname: Lindau
mesh_terms: D000199:Actins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000648:ultrastructure; D002837:Chromaffin Granules / Q000187:drug effects / Q000378:metabolism*; D015638:Cytochalasin D / Q000494:pharmacology; D025802:Electric Capacitance; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D018613:Microscopy, Confocal / Q000379:methods; D024462:Myosin Type II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009281:Naphthalenes / Q000494:pharmacology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology
chemical_list: D000199:Actins; D001381:Azepines; D002395:Catecholamines; D006576:Heterocyclic Compounds, 4 or More Rings; D009281:Naphthalenes; D019384:Nucleic Acid Synthesis Inhibitors; C070571:ML 7; C472645:blebbistatin; D015638:Cytochalasin D; D024462:Myosin Type II