Effect of ofloxacin on the uptake of [3H]thymidine by articular cartilage cells in the rat.

Ofloxacin (900 mg/kg) was orally administered to Sprague-Dawley rats aged 4 weeks. A single dosage induced chondrocyte degeneration in the middle zone of the articular cartilage 5 h later and cavity formation 12 and 24 h later. The number of cells labeled with [3H]thymidine was decreased in histologically normal and abnormal cartilage at 5 h. Incorporation rate of [3H]thymidine into the articular cartilage was gradually decreased until 12 h later, but increased above the control level at 24 h. Another experiment showed that labeled cells were retained for a longer period than in control rats in the middle zone at the predilection site of osteochondrosis.