The effect and interaction of bradykinin and prostaglandins on protein and collagen production by lung fibroblasts.

Bradykinin stimulates protein production as well as prostaglandin production by lung fibroblasts in culture. When prostaglandin (PG) synthesis by the fibroblasts is inhibited with indomethacin, then bradykinin also stimulates collagen production. In the presence of indomethacin, the increase in protein production by bradykinin is much higher than in its absence. The addition of exogenous PGE2 to the fibroblasts which have been treated with indomethacin inhibited the stimulating effect of bradykinin on total protein production, especially collagen production. The concentration of PGE2 added was in the range of that produced by the fibroblasts. The degree of inhibition by PGE2 was dependent on the concentration of PGE2 added to the cultures. These results point out an interaction between bradykinin and PGE2 in the regulation of protein production by fibroblasts with PGE2 acting as a feedback mechanism to dampen the effect of bradykinin.