Hydroxyl radical activation of a Ca -sensitive nonselective cation channel involved in epithelial cell necrosis
نویسندگان
چکیده
Simon, Felipe, Diego Varela, Ana Luisa Eguiguren, Laı́n F. Dı́az, Francisco Sala, and Andrés Stutzin. Hydroxyl radical activation of a Ca -sensitive nonselective cation channel involved in epithelial cell necrosis. Am J Physiol Cell Physiol 287: C963–C970, 2004. First published May 26, 2004; 10.1152/ajpcell.00041.2004.—In a previous work the involvement of a fenamate-sensitive Ca activated nonselective cation channel (NSCC) in free radical-induced rat liver cell necrosis was demonstrated (5). Therefore, we studied the effect of radical oxygen species and oxidizing agents on the gating behavior of a NSCC in a liver-derived epithelial cell line (HTC). Single-channel currents were recorded in HTC cells by the excised inside-out configuration of the patch-clamp technique. In this cell line, we characterize a 19-pS Ca -activated, ATPand fenamate-sensitive NSCC nearly equally permeable to monovalent cations. In the presence of Fe , exposure of the intracellular side of NSCC to H2O2 increased their open probability (Po) by 40% without affecting the unitary conductance. Desferrioxamine as well as the hydroxyl radical ( OH) scavenger MCI-186 inhibited the effect of H2O2, indicating that the increase in Po was mediated by OH. Exposure of the patch membrane to the oxidizing agent 5,5 -dithio-bis-2-nitrobenzoic acid (DTNB) had a similar effect to OH. The increase in Po induced by OH or DTNB was not reverted by preventing formation or by DTNB washout, respectively. However, the reducing agent dithiothreitol completely reversed the effects on Po of both OH and DTNB. A similar increase in Po was observed by applying the physiological oxidizing molecule GSSG. Moreover, GSSG-oxidized channels showed enhanced sensitivity to Ca . The effect of GSSG was fully reversed by GSH. These results suggest an intracellular site(s) of action of oxidizing agents on cysteine targets on the fenamatesensitive NSCC protein implicated in epithelial cell necrosis.
منابع مشابه
Hydroxyl radical activation of a Ca(2+)-sensitive nonselective cation channel involved in epithelial cell necrosis.
In a previous work the involvement of a fenamate-sensitive Ca(2+)-activated nonselective cation channel (NSCC) in free radical-induced rat liver cell necrosis was demonstrated (5). Therefore, we studied the effect of radical oxygen species and oxidizing agents on the gating behavior of a NSCC in a liver-derived epithelial cell line (HTC). Single-channel currents were recorded in HTC cells by th...
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