Inhibition of gastric H+,K+-ATPase by 4-(2-butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)oxybutyric acid (DCPIB), an inhibitor of volume-regulated anion channel.
4-(2-Butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)oxybutyric acid (DCPIB) has been used as an inhibitor of volume-regulated anion channel (VRAC), which is expressed in almost all cells (IC50 is around 4 µM). Here, we found that DCPIB significantly inhibited the activities of gastric proton pump (H+,K+-ATPase) in isolated gastric tubulovesicles and the membrane sample of the H+,K+-ATPase-expressing cells, and their IC50 values were around 9 µM. In the tubulovesicles, no significant expression of leucine rich repeat containing 8 family member A (LRRC8A), an essential component of VRAC, was observed. The inhibitory effect of DCPIB was also found in the membrane sample obtained from the cells in which LRRC8A had been knocked down. On the other hand, DCPIB had no significant effect on the activity of Na+,K+-ATPase or Ca2+-ATPase. In the H+,K+-ATPase-expressing cells, DCPIB inhibited the 86Rb+ transport activity of H+,K+-ATPase but not that of Na+,K+-ATPase. DCPIB had no effect on the activity of Cl- channels other than VRAC in the cells. These results suggest that DCPIB directly inhibits H+,K+-ATPase activity. DCPIB may be a beneficial tool for studying the H+,K+-ATPase function in vitro.
Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
Takuto
T
Fujii
Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
Yuji
Y
Takahashi
Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
Hiroshi
H
Takeshima
Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
Chisato
C
Saitoh
Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
Takahiro
T
Shimizu
Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
Noriaki
N
Takeguchi
Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan. Electronic address: sakaih@pha.u-toyama.ac.jp.
Hideki
H
Sakai
D000818:Animals; D003517:Cyclopentanes / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D017506:H(+)-K(+)-Exchanging ATPase / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007189:Indans / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology; D018374:LLC-PK1 Cells; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D054328:Proton Pump Inhibitors / Q000494:pharmacology*; D013552:Swine
C443139:4-(2-butyl-6,7-dichlor-2-cyclopentyl-indan-1-one-5-yl)oxybutyric acid; D003517:Cyclopentanes; D007189:Indans; C485976:LRRC8A protein, human; D008565:Membrane Proteins; D054328:Proton Pump Inhibitors; D017506:H(+)-K(+)-Exchanging ATPase
DCPIB; H(+),K(+)-ATPase; LRRC8A; Proton pump; Volume-regulated anion channel