T. Inaba et al., HISTOCHEMISTRY OF CYCLIC-NUCLEOTIDE METABOLIZING ENZYMES IN OSTEOARTHRITIS, Acta histochemica et cytochemica, 30(3), 1997, pp. 257-269
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.