POSSIBLE INVOLVEMENT OF NITRIC-OXIDE IN THE QUINOLONE-INDUCED TENDON LESIONS IN RATS

Quinolone antibacterial agents have been reported to induce adverse ef fects on the tendon and the musculoskeletal system in humans. We have previously demonstrated that Achilles tendon lesions could be induced in juvenile rats by a single oral administration of quinolones at high doses with simultaneous induction oi lesions in the muscle, synovial membrane and articular cartilage, in the present investigation we exam ined the involvement of nitric oxide (NO) in pefloxacin (PFLX)-induced lesions of the Achilles tendon in juvenile rats. The incidence of les ions was diminished markedly by cc-administration of a potent NO synth ase inhibitor; N-nitro-L-arginine methyl ester (L-NAME). Further, the urinary nitrate/nitrite excretion was decreased significantly by 4h af ter administration, unchanged between 4 and 8h, and significantly incr eased in the 8- to 24-h samples in the PFLX group, as compared to the control group. in contrast, the serum concentration oi nitrate/nitrite was significantly higher in the PFLX group 4 h after administration, but there was no difference from controls was observed at 8 and 24 h. These results suggest that NO is involved in the induction of Achilles tendon lesions in juvenile rats by pefloxacin (PFLX) and may be simil ar to the tendon disorder of humans receiving quinolones.