HISTOCHEMISTRY OF CYCLIC-NUCLEOTIDE METABOLIZING ENZYMES IN OSTEOARTHRITIS

Cyclic nucleotide metabolizing enzymes were studied cytochemically to estimate the changes in these enzymes in the synovial membrane, becaus e one of the functions of this tissue is estimated to clean up the deb ris from the synovial fluid to facilitate lubrication in the knee join ts by filtering up small fragments of cartilage which have been formed as the result of wear and tear from the articular cartilage in osteoa rthritis. Since the cyclic nucleotides are assumed to regulate the bio logical activity of phagocytosis, it may be reasonable to expect chang es in this activity during the disability of osteoarthritis. In normal and osteoarthritic synovial membranes, a high adenylate cyclase (ACas e) 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 undernea th. The activity of guanylate cyclase (GCase) was observed to be rathe r weak; however, a strong 5'-nucleotidase (5'-N) activity was evidence d, indicating the existence of a regulatory function with the cyclic n ucleotides in the phagocytotic and pinocytotic activities during osteo arthritis.