Objective—To study chondrotoxic effects of enrofloxacin (ENR) and ciprofloxacin hydrochloride (CFX) on canine and equine articular chondrocytes in culture and to compare the effects with that of cultivation in Mg2+-free medium.
Sample Population—Chondrocytes from articular cartilage of 4- and 6 -month old dogs and 2- to 4- year-old horses.
Procedure—Chondrocytes were cultivated with 10, 40, 80, and 160 μg of CFX/ml, 10, 50, 100, and 150 μg of ENR/ml, or in Mg2+-free medium. A live-to-dead test was performed to test cytotoxic effects. Morphologic changes were evaluated by electron microscopy. An attachment assay was used to test the ability of chondrocytes to adhere to collagen type- II coated-chamber slides in the presence of CFX and with Mg2+-free medium.
Results—Chondrocytes cultivated in quinolone-supplemented medium or Mg2+-free medium had a decreased ability to adhere to culture dishes. Cell shape and the actin and vimentin cytoskeleton changed in a concentration-dependent manner. These effects were not species-specific and developed with both quinolones. On day 1 of culture, adhesion of chondrocytes to collagen type II was reduced to 70 and 45% of control values in the CFX treatment and Mg2+-free treatment groups, respectively. On day 5 of culture, adhesion of chondrocytes was reduced to 45 and 40% of control values in the CFX treatment and Mg2+-free treatment groups, respectively.
Conclusion and Clinical Relevance—In vitro, chondrotoxic effects of quinolones appear to be the result of irregular integrin signaling and subsequent cellular changes. Drug concentrations leading to morphologic changes in vitro may be achieved in articular cartilage in vivo. (Am J Vet Res 2001;62:704–708)