Metabolic effects of lathyrogenic agents on cartilage in vivo and in vitro.

The effects of lathyrogenic agents in vivo and in vitro are described, in respect to some biochemical indices of cartilage metabolism. Lathyrogenic agents in vivo inhibited the incorporation of radiosulfate into rat epiphyseal cartilage and the isolated chondroitin sulfate. No significant changes in hydroxyproline or hexosamine content of epiphyseal cartilage were found, but there was a marked increase in water content. The content of chondroitin sulfate, measured as uronic acid, was decreased. The importance of taking growth rate differences between control and experimental rats into account in assessing the effects of lathyrogenic agents in vivo is emphasized. In an in vitro system, utilizing fresh calf costal cartilage slices, the presence of low concentrations of lathyrogenic agents markedly affected various metabolic events. The incorporation into cartilage slices of sulfate-S(35), glucose-U-C(14), and glycine-1-C(14) was significantly depressed, as was the production of organic acids, including lactic acid. In general, these effects were more severe under anaerobic conditions. Glutamine restored the activities of the slices treated with lathyrogenic agents to control values obtained in the absence of either lathyrogen or glutamine.