Glycine-gated chloride channels in neutrophils attenuate calcium influx and superoxide production

FASEB J. 2000 Mar;14(3):476-84. doi: 10.1096/fasebj.14.3.476.


Recently, it was demonstrated that liver injury and TNF-alpha production as a result of endotoxin (lipopolysaccharide, LPS) were attenuated by feeding animals a diet enriched with glycine. This phenomenon was shown to be a result of, at least in part, activation of a chloride channel in Kupffer cells by glycine, which hyperpolarizes the cell membrane and blunts increases in intracellular calcium concentrations ([Ca(2+)](i)) similar to its action in the neuron. It is well known that hepatotoxicity due to LPS has a neutrophil-mediated component and that activation of neutrophils is dependent on increases in [Ca(2+)](i). Therefore, the purpose of this study was to determine if glycine affected agonist-induced increases in [Ca(2+)](i) in rat neutrophils. The effect of glycine on increases in [Ca(2+)](i) elicited either by the bacterial-derived peptide formyl-methionine-leucine-phenylalanine (FMLP) or LPS was studied in individual neutrophils using Fura-2 and fluorescence microscopy. Both FMLP and LPS caused dose-dependent increases in [Ca(2+)](i), which were maximal at 1 microM FMLP and 100 microgram/ml LPS, respectively. LPS increased intracellular calcium in the presence and absence of extracellular calcium. Glycine blunted increases in [Ca(2+)](i) in a dose-dependent manner with an IC(50) of approximately 0.3 mM, values only slightly higher than plasma levels. Glycine was unable to prevent agonist-induced increases in [Ca(2+)](i) in chloride-free buffer. Moreover, strychnine (1 microM), an antagonist of the glycine-gated chloride channel in the central nervous system, reversed the effects of glycine (1 mM) on FMLP- or LPS-stimulated increases in [Ca(2+)](i). To provide hard evidence for a glycine-gated chloride channel in the neutrophil, the effect of glycine on radioactive chloride uptake was determined. Glycine caused a dose-dependent increase in chloride uptake into neutrophils with an ED(50) of approximately 0.4 mM, an effect also prevented by 1 microM strychnine. Glycine also significantly reduced the production of superoxide anion from FMLP-stimulated neutrophils. Taken together, these data provide clear evidence that neutrophils contain a glycine-gated chloride channel that can attenuate increases in [Ca(2+)](i) and diminish oxidant production by this important leukocyte.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cell Adhesion
  • Chloride Channel Agonists
  • Chloride Channels / blood*
  • Chlorides / blood
  • Chlorides / pharmacology
  • Egtazic Acid / pharmacology
  • Female
  • Glycine / pharmacology*
  • Kinetics
  • Lipopolysaccharides / pharmacology
  • N-Formylmethionine Leucyl-Phenylalanine / pharmacology
  • Neutrophils / drug effects
  • Neutrophils / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Strychnine / pharmacology
  • Superoxides / blood*


  • Chloride Channel Agonists
  • Chloride Channels
  • Chlorides
  • Lipopolysaccharides
  • Superoxides
  • Egtazic Acid
  • N-Formylmethionine Leucyl-Phenylalanine
  • Strychnine
  • Calcium
  • Glycine