Molecular characterisation of cloned bradykinin B1 receptors from rat and human.

This report describes the characterisation of cloned rat and human bradykinin B1 receptors in African green monkey kidney fibroblast (Cos-7) cells. A ligand binding assay with [3H]des-Arg10-kallidin was used to compare their pharmacology with respect to known bradykinin B1 and B2 receptor ligands. In addition, the pharmacology of T-kinin and its' derivative des-Arg11-T-kinin was investigated. The cloned rat receptor had a similar pharmacology to that of the recently described mouse receptor and differs from that described for the human receptor. The rat receptor had a higher affinity for des-Arg11-T-kinin than the human receptor. These differences in pharmacological properties may relate to the presence of T-kinin, bradykinin and their des-Arg derivatives as the major physiological peptides in rat and the predominance of kallidin and its derivatives in human. We confirm that the rat bradykinin B1 receptor gene is organised in a two exon structure and differs from the human gene which has a three exon structure and we further examine the inducible expression of this gene in a wide range of tissues using Northern blotting.