Enzyme histochemical changes in murine osteoarthritis.

Male mice of the STR/ORT strain spontaneously develop an osteoarthritic lesion in the medial tibial condyles. Histochemical studies of lactate dehydrogenase have previously shown that a region of completely inactive chondrocytes develops in the cartilage prior to degenerative changes. The present studies have shown a nearly parallel time course for the development of inactive cells and cartilage damage, except that there is a delay of four to five weeks between these two events. It is considered that the latter is a consequence of the former. The mechanism of the enzyme depletion is not known, but it probably extends to many, if not all, oxidative enzymes, and it is suggested that a disturbance in a hydrogen transport (cytochrome) system could account for the apparent lack of activity of many dehydrogenases as demonstrated by tetrazolium salt techniques.