Leukotriene D4 activates a chloride conductance in hepatocytes from lipopolysaccharide-treated rats.
Endotoxin (LPS) can cause hepatocellular injury under several circumstances, and leukotrienes have been implicated as a contributing factor. Since ion channel activation has been associated with cytotoxicity, the aim of this study was to determine the circumstances under which LPS and/or leukotrienes activate ionic conductances in hepatocytes. LPS treatment of rats increased Cl- conductance in hepatocytes from 232+/-42 to 1236+/-134 pS/pF. Voltage dependence and inhibitor specificity of this conductance were similar to that of a swelling-activated Cl- conductance, and internal dialysis with nucleoside analogues suggested control by an inhibitory G protein. The lipoxygenase inhibitor nordihydroguaiaretic acid, the specific leukotriene D4 (LTD4) receptor antagonist MK-571, and the 5-lipoxygenase activating protein inhibitor MK-886 all significantly inhibited the conductance. Intracellular dialysis with LTD4 (1.5 microM) elevated intracellular Ca2+ from 143+/-6.5 to 388+/-114 nM within 6 min and stimulated an outwardly rectifying conductance from 642+/-159 to 1669+/-224 pS/pF (n = 9, P < 0.001). In hepatocytes prepared from untreated rats, this concentration of intracellular LTD4 neither raised intracellular Ca2+ nor activated the conductance. The LTD4 response could be induced in normal hepatocytes by culture with either conditioned medium from LPS-treated macrophages or purified TNF-alpha. In conclusion, intracellular LTD4 activates a chloride conductance in hepatocytes isolated from rats treated with LPS or primed in vitro with TNF-alpha. Changes in the hepatocellular accumulation of leukotrienes therefore mediate channel activation and may contribute to liver injury during sepsis and other inflammatory conditions.
Meng
X J
XJ
Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas 77555-0641, USA.
Carruth
M W
MW
Weinman
S A
SA
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D017077:Culture Media, Conditioned; D004553:Electric Conductivity; D004926:Escherichia coli; D020024:Leukotriene Antagonists; D017998:Leukotriene D4 / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008099:Liver / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D018077:Receptors, Leukotriene; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D018118:Chloride Channels; D017077:Culture Media, Conditioned; D020024:Leukotriene Antagonists; D008070:Lipopolysaccharides; D016859:Lipoxygenase Inhibitors; D008565:Membrane Proteins; D018077:Receptors, Leukotriene; D014409:Tumor Necrosis Factor-alpha; D017998:Leukotriene D4; C412375:cysteinyl leukotriene receptor 2; C083169:leukotriene D4 receptor; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium