Expression of bradykinin B1 receptors in colonic epithelia

The rat colonic epithelium shows no response to [des-Arg9] bradykinin (DAB) in newly isolated tissues, but does so after 3 h in vitro. The EC50 for DAB is circa 50 nM and the maximal response is 57.8 +/- 5.3 microA cm-2 (n = 68). The whole of the current increase is sensitive to frusemide and is predominantly due to electrogenic chloride secretion. The development of responsiveness is prevented by inhibitors of translation (cycloheximide) and transcription (actinomycin D). Thus the receptor for DAB has the hall marks of a classical B1 kinin receptor. While the classical B2 kinin receptor antagonist HOE140, has no effect on the responses, the classical B1 kinin receptor antagonist, [Leu8]DAB, behaves as an agonist in this system. It is concluded that there may be more than one type of B1 kinin receptor.