Glycine blocks opening of a death channel in cultured hepatic sinusoidal endothelial cells during chemical hypoxia.
Using confocal microscopy, we investigated mechanisms underlying loss of plasma membrane integrity during necrotic death of cultured hepatic sinusoidal endothelial cells exposed to 2.5 mM potassium cyanide (chemical hypoxia). After 2-3 h, the anionic fluorophore calcein abruptly began to enter the cytosol, and nuclei labeled with cationic propidium after another 2-5 min. As calcein permeated, growth of blebs on the plasma membrane accelerated. Lucifer yellow, another anionic fluorophore, entered identically to calcein, whereas high molecular weight dextrans (40-2000 kDa) entered like propidium. Glycine slowed, but did not prevent calcein entry, whereas permeation of propidium and high molecular weight dextrans was blocked completely by glycine. These findings suggest that opening of a glycine-sensitive organic anion channel, or death channel, precipitates a metastable state characterized by rapid cell swelling and bleb growth. This metastable state culminates in non-specific breakdown of the plasma membrane permeability barrier and irreversible cell death.
Nishimura
Y
Y
Department of Cell Biology & Anatomy, School of Medicine, University of North Carolina at Chapel Hill, 27599-7090, USA.
Lemasters
J J
JJ
D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D005998:Glycine / Q000494:pharmacology*; D006801:Humans; D007473:Ion Channels / Q000187:drug effects* / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011190:Potassium Cyanide / Q000494:pharmacology
D005456:Fluorescent Dyes; D007473:Ion Channels; D011190:Potassium Cyanide; D005998:Glycine