Bradykinin action in the rat duodenum: Ca2(+)-dependent effects of bradykinin on the activity of particulate guanylate cyclase.

The nonapeptide bradykinin has been found to exert opposite effects on cGMP synthesis in a plasma membrane fraction from the rat duodenum. In the absence of exogenous Ca2+ BK increased the activity of the duodenal particulate guanylate cyclase which is decreased, in contrast, in a medium containing 1 mM exogenous Ca2+. In a Ca2(+)-free medium, on the other hand, both BK effects are completely prevented. The results suggest a presumable role of pGC in BK signal transmission in the rat duodenum with calcium ions as a mediator and/or essential cofactor.