Abstract
The purpose of this paper is to present the results of enzymo-histochemical study which has been carried out to clarify the influence of immobilization upon the joint cartilage and synovial membrane in matured rabbits.
The right knees of 30 matured male rabbits were immobilized by plaster cast in 90 degree including ankle joints.
The left knees were served as controls. The animals were sacrificed, dividing into three groups, at 2 weeks, 4 weeks and 6 weeks after immobilization, and then enzymatic activities of acid phosphatase, alkaline phosphatase, malate dehydrogenase, lactate dehydrogenase, N-acetyl-β-glucosaminidase and peroxidase were observed in specimens obtained joint cartilage and synovial membrane by means of cryostat.
Outstanding findings were summarized as follows:
1. Acid phosphatase activity was observed in all part of the joint cartilages. 2 weeks after the beginning of the immobilization, the activities of acid phosphatase began to be depressed before the beginning of the histological changes of the joint cartilages.
2. Alkaline phosphatase was localized in the basal zone of the joint cartilages, and the activities of the enzyme were not seriously affected by immobilization for at least 4 weeks. The metabolic function of alkaline phosphatase may be different from that of acid phosphatase, according to the difference of the localization of both enzymes and the distinction of the influence of immobilization upon these enzymes.
3. Malate dehydrogenase and lactate dehydrogenase were observed in all layers of the joint cartilage, and the activities of these enzymes did not depress even after 4 weeks of immobilization. This result suggests that the metabolism of glycolysis and T. C. A cycle in joint cartilage is maintained for comparatively long period after immobilization.
4. Acid phosphatase and N-acetyl-β-glucosaminidase were localizcd in the linning cells of the synovial membranes, and the early stages of absorption of horseradish peroxidase injected into the joint cavity were studied by means of an enzymatic histochemical technique. The activation of these two enzymes was observed at the early stages of absorption of horseradish peroxidase, but this finding was not observed by the influence of the immobilization for 4 weeks.
From these findings, the enzymatic histochemical study of the joint cartilage and the synovial membrane may contribute to the understanding of a close relation between disuse atrophy of the joint and the metabolic dysfunctions.
