F-actin and myosin II accelerate catecholamine release from chromaffin granules.
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.
Berberian
Khajak
K
School of Applied and Engineering Physics, and Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
Torres
Alexis J
AJ
Fang
Qinghua
Q
Kisler
Kassandra
K
Lindau
Manfred
M
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
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