Stimulation of alpha-(methylamino) isobutyric acid uptake by interleukin-1 in human synovial cells. Involvement of a cAMP dependent pathway.

: After one hour incubation with interleukin-1 beta (IL-1 beta), the uptake of alpha-(methylamino) isobutyric acid (MeAIB) by human osteoarthritic synovial cells appeared significantly increased. This effect, observed with 0.1 to 5 ng/ml of cytokine, was inhibited by cycloheximide, indicating that protein synthesis is involved. In addition, this effect seems mediated by a pertussis toxin-sensitive G protein. Finally, intracellular cAMP concentration measurements, the use of a phorbol ester, protein kinase inhibitors and forskolin+3-isobutyl-1-methylxantine (IBMX) provided evidence that a cAMP-dependent protein kinase is associated with interleukin-1 beta-mediated alpha-(methylamino) isobutyric acid uptake.