Effect of nalidixic acid, pipemidic acid and cinoxacin on chondrocyte metabolism in explants of articular cartilage.

Explants of immature bovine articular cartilage were exposed to nalidixic acid, pipemidic acid and cinoxacin at one and ten times the human therapeutic plasma level for 7 days. Only nalidixic acid had significant effects on the chondrocyte metabolism. 20 micrograms/ml nalidixic acid caused an increase of 35S-sulfate incorporation into glycosaminoglycans at day 7. Two hundred micrograms/ml nalidixic acid inhibited the incorporation of 3H-thymidine into DNA. The incorporation of 35S-sulfate into glycosaminoglycans was decreased at day 0, while at day 7 the incorporation had returned to the control value. Pipemidic acid and cinoxacin had no significant effects on either the 3H-thymidine or the 35S-sulfate incorporation.