Quantal release of free radicals during exocytosis of phagosomes.
Secretion of lysosomes and related organelles is important for immune system function. High-resolution membrane capacitance techniques were used to track changes in membrane area in single phagocytes during opsonized polystyrene bead uptake and release. Secretagogue stimulation of cells preloaded with beads resulted in immediate vesicle discharge, visualized as step increases in capacitance. The size of the increases were consistent with phagosome size. This hypothesis was confirmed by direct observation of dye release from bead-containing phagosomes after secretagogue stimulation. Capacitance recordings of exocytosis were correlated with quantal free radical release, as determined by amperometry. Thus, phagosomes undergo regulated secretion in macrophages, one function of which may be to deliver sequestered free radicals to the extracellular space.
Di
Anke
A
Department of Neurobiology, Pharmacology and Physiology, The University of Chicago, Chicago, IL 60637, USA.
Krupa
Boris
B
Bindokas
Vytas P
VP
Chen
Yimei
Y
Brown
Mary E
ME
Palfrey
H Clive
HC
Naren
Anjaparavanda P
AP
Kirk
Kevin L
KL
Nelson
Deborah J
DJ
D000818:Animals; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D004594:Electrophysiology; D005089:Exocytosis; D005609:Free Radicals; D005982:Glutathione Transferase / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D010588:Phagosomes / Q000378:metabolism*; D050765:Qa-SNARE Proteins; D011796:Quinacrine / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D050600:SNARE Proteins; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors; D033921:Vesicular Transport Proteins
D018076:DNA, Complementary; D005609:Free Radicals; D007074:Immunoglobulin G; D008565:Membrane Proteins; D050765:Qa-SNARE Proteins; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; D033921:Vesicular Transport Proteins; D013481:Superoxides; D006160:Guanosine Triphosphate; D005982:Glutathione Transferase; D011796:Quinacrine