Inhibition of the Endogenous Volume-regulated Anion Channel (VRAC) in HEK293 Cells by Acidic Di-Aryl-Ureas

Inhibition of the Endogenous Volume-regulated Anion Channel (VRAC) in HEK293 Cells by Acidic... The endogenous volume-regulated anion channel (VRAC) from HEK293 cells was pharmacologically characterized using the whole-cell patch-clamp technique. Under isotonic conditions a small (1.3 nS), Ca2+-independent Cl conductance was measured. However, swelling at 75% tonicity activated a VRAC identified as an outward-rectifying anion current (P l > P Cl > P gluconate), which was ATP-dependent and showed inactivation at positive potentials. Activation of this current followed a sigmoid time course, reaching a plateau conductance of 42.6 nS after 12–15 min (t 1/2 = 7 min). The pharmacology of this VRAC was investigated using standard Cl−-channel blockers (NPPB, DIDS, and tamoxifen) as well as a new group (acidic di-aryl ureas) of Cl−-channel blockers (NS1652, NS3623, NS3749, and NS3728). The acidic di-aryl ureas were originally synthezised for inhibition of the human erythrocyte Cl− conductance in vivo. NS3728 was the most potent VRAC blocker in this series (IC 50 = 0.40 µM) and even more potent than tamoxifen (2.2 µM). NS3728 accelerated channel inactivation at positive potentials. These results show that acidic di-aryl ureas constitute a promising starting point for the synthesis of potent inhibitors of VRAC. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Inhibition of the Endogenous Volume-regulated Anion Channel (VRAC) in HEK293 Cells by Acidic Di-Aryl-Ureas

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Publisher
Springer-Verlag
Copyright
Copyright © 2003 by Springer-Verlag New York Inc.
Subject
Philosophy
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-003-0627-x
Publisher site
See Article on Publisher Site

Abstract

The endogenous volume-regulated anion channel (VRAC) from HEK293 cells was pharmacologically characterized using the whole-cell patch-clamp technique. Under isotonic conditions a small (1.3 nS), Ca2+-independent Cl conductance was measured. However, swelling at 75% tonicity activated a VRAC identified as an outward-rectifying anion current (P l > P Cl > P gluconate), which was ATP-dependent and showed inactivation at positive potentials. Activation of this current followed a sigmoid time course, reaching a plateau conductance of 42.6 nS after 12–15 min (t 1/2 = 7 min). The pharmacology of this VRAC was investigated using standard Cl−-channel blockers (NPPB, DIDS, and tamoxifen) as well as a new group (acidic di-aryl ureas) of Cl−-channel blockers (NS1652, NS3623, NS3749, and NS3728). The acidic di-aryl ureas were originally synthezised for inhibition of the human erythrocyte Cl− conductance in vivo. NS3728 was the most potent VRAC blocker in this series (IC 50 = 0.40 µM) and even more potent than tamoxifen (2.2 µM). NS3728 accelerated channel inactivation at positive potentials. These results show that acidic di-aryl ureas constitute a promising starting point for the synthesis of potent inhibitors of VRAC.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jan 1, 2003

References

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