Inhibition of acid-sensing ion channels in articular chondrocytes by amiloride attenuates articular cartilage destruction in rats with adjuvant arthritis.
OBJECTIVE
The aim of this study was to examine whether drugs such as amiloride that block acid sensing ion channels (ASICs) could attenuate articular cartilage destruction in adjuvant-induced arthritis (AA).


METHODS
Articular chondrocytes were isolated from the normal rats, and intracellular calcium ([Ca(2+)]i) was analyzed with laser scanning confocal microscopy. The cell injury was analyzed with lactate dehydrogenase release assay and electron microscopy. Amiloride or phosphate buffered saline was administered daily to AA rats for 1 week from the time of arthritis onset. Morphology of the articular cartilage was examined by hematoxylin and eosin staining, and Mankin score was calculated. The expression level of type II collagen (COII) and aggrecan mRNA and proteins in the articular cartilage was evaluated by real-time PCR and Western blotting, respectively.


RESULTS
The rapid decrease in extracellular pH (6.0) induced a conspicuous increase in [Ca(2+)]i in the articular chondrocytes. Amiloride reduced this increase in [Ca(2+)]i, and inhibited acid-induced articular chondrocyte injury. Amiloride significantly decreased Mankin scores in the articular cartilage in AA rats. COII and aggrecan mRNA and protein expression in the articular cartilage was significantly increased by amiloride.


CONCLUSIONS
These findings represent some experimental evidence of a potential role for ASICs in the pathogenesis of articular cartilage destruction in rheumatoid arthritis.
Yuan
Feng-Lai
FL
College of Pharmacy, Anhui Medical University, Hefei, Anhui, People's Republic of China. bjjq88@163.com
Chen
Fei-Hu
FH
Lu
Wei-Guo
WG
Li
Xia
X
Li
Jian-Ping
JP
Li
Cheng-Wan
CW
Xu
Rui-Sheng
RS
Wu
Fan-Rong
FR
Hu
Wei
W
Zhang
Teng-Yue
TY
D062565:Acid Sensing Ion Channels; D053674:Aggrecans / Q000378:metabolism; D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D001169:Arthritis, Experimental / Q000378:metabolism / Q000473:pathology*; D002358:Cartilage, Articular / Q000166:cytology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology*; D015222:Sodium Channels / Q000378:metabolism*
D062565:Acid Sensing Ion Channels; D053674:Aggrecans; D024043:Collagen Type II; D009419:Nerve Tissue Proteins; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D000584:Amiloride
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