PROTEIN-KINASE-C MODULATES THE SYNTHESIS OF NITRIC-OXIDE BY OSTEOBLASTS

To determine the involvement of protein kinase C (PKC) in nitric oxide (NO) synthesis of osteoblast, a combination of proinflammatory cytoki nes (tumor necrosis factor-alpha, interferon-gamma, bacterial lipopoly saccharide) were added on rat osteoblast-like cells. Results show that these cytokines clearly enhanced the synthesis of NO. The activation of PKC with phorbol ester also resulted iu the stimulation of NO synth esis in these cells. These cytokines activated PKC and increased the l evels of intracellular Ca2+. In addition, the cytokine-induced synthes is of NO was blocked by PKC inhibitors. Findings suggest the involveme nt of PKC in the synthesis of NO by rat osteoblasts.