Bradykinin activates sphingolipid metabolism. Fibroblasts treated with bradykinin produce a rapid and important increase in ceramide which is followed by a transient rise in sphingosine content. The peptide also increases ceramide cellular content by rapidly mobilizing neutral glycolipids. Bradykinin plays an important role in the regulation of fluid and electrolyte balance, smooth muscle contraction, vasodilation and capillary permeability. The bradykinin potentiators, which possess no bradykinin activity themselves, enhance the activity of bradykinin.