Inhibition of small-conductance Cl- channels by the interleukin-1beta-stimulated production of superoxide in rabbit gastric parietal cells.
We have shown previously that the G protein-coupled production of superoxide anion (O2-) leads to closure of small-conductance Cl- channels (0.3-0.4 pS) in the basolateral membrane of rabbit parietal cells. In the present study, effects of interleukin-1beta (IL-1beta) on the Cl- channel were investigated. In the whole-cell patch-clamp recording, IL-1beta (0.3-10 ng ml-1) inhibited the whole-cell Cl- current recorded from a parietal cell within isolated rabbit gastric glands. Variance noise analysis of the whole-cell Cl- current showed that the single channel conductance of the Cl- channel that is sensitive to IL-1beta is 0.37 pS. The IL-1beta (1 ng ml-1)-induced decrease of the Cl- current was abolished by anti-IL-1beta antibody (2 microg ml-1), recombinant IL-1 receptor antagonist (500 ng ml-1), GDPbetaS (500 microM) and superoxide dismutase (100 units ml-1), a scavenger of O2-. Northern blot analysis showed that the mRNA of the IL-1 receptor was selectively expressed in rabbit gastric parietal cells. In the dihydrofluorescein diacetate-loaded single parietal cells in gastric glands, IL-1beta (0.3-10 ng ml-1) stimulated the production of oxygen radicals. Y-27632 (1-10 microM), a specific Rho-kinase inhibitor, and fluvastatin (10 microM), an indirect inhibitor for Rho proteins, significantly inhibited the IL-1beta-induced effects on the channel activity and production of oxygen radicals. IL-1beta (0.3-10 ng ml-1) activated Rho in the parietal cells. These results indicate that IL-1beta binds to the IL-1 receptor of gastric parietal cells and inhibits the small-conductance Cl- channel via the G protein-mediated Rho/Rho-kinase-dependent production of O2-.
Sakai
Hideki
H
Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan. sakaih@ms.toyama-mpu.ac.jp
Ohira
Yuta
Y
Tanaka
Akiko
A
Suzuki
Tomoyuki
T
Ikari
Akira
A
Morii
Magotoshi
M
Takeguchi
Noriaki
N
D000209:Acute-Phase Proteins / Q000187:drug effects / Q000502:physiology; D000818:Animals; D018118:Chloride Channels / Q000037:antagonists & inhibitors* / Q000502:physiology; D004553:Electric Conductivity; D019204:GTP-Binding Proteins / Q000502:physiology; D007375:Interleukin-1 / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D054460:rho-Associated Kinases
D000209:Acute-Phase Proteins; D018118:Chloride Channels; D007375:Interleukin-1; D047908:Intracellular Signaling Peptides and Proteins; D017382:Reactive Oxygen Species; C010781:acute-phase protein rho; D013481:Superoxides; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D019204:GTP-Binding Proteins