Abstract
Cyclic nucleotide metabolizing enzymes were studied cytochemically to estimate the changes in these enzymes in the synovial membrane, because one of the functions of this tissue is estimated to clean up the debris from the synovial fluid to facilitate lubrication in the knee joints by filtering up small fragments of cartilage which have been formed as the result of wear and tear from the articular cartilage in osteoarthritis. Since the cyclic nucleotides are assumed to regulate the biological activity of phagocytosis, it may be reasonable to expect changes in this activity during the disability of osteoarthritis. In normal and osteoarthritic synovial membranes, a high adenylate cyclase (ACase) activity was clearly observed in the A cells at the surface of the synovial membrane, positive on the plasma membranes of the microvilli and on the ruffled borders as well as in pinocytotic vesicles underneath. The activity of guanylate cyclase (GCase) was observed to be rather weak; however, a strong 5′-nucleotidase (5′-N) activity was evidenced, indicating the existence of a regulatory function with the cyclic nucleotides in the phagocytotic and pinocytotic activities during osteoarthritis.
