CLONING, SEQUENCING AND FUNCTIONAL EXPRESSION OF A GUINEA-PIG LUNG BRADYKININ B-2 RECEPTOR

Kinin receptors are classified as B-1 and B-2 based upon agonist and a ntagonist potencies and cloning and expression studies. Using sequence s from human and rat bradykinin B-2 receptors, polymerase chain reacti on (PCR) was utilized to isolate cDNA from guinea pig lung. The recept or obtained is predicted to have 372 amino acids and shares > 80% sequ ence homology with human, rat, rabbit and mouse B-2 receptors. In comp etition binding experiments in Chinese hamster ovary (CHO-KI) cells in which the guinea pig cDNA was expressed, [H-3]bradykinin was displace d by kinin receptor ligands with an order of potency consistent with a B-2 subtype. In CHO cells expressing the guinea pig receptor, bradyki nin caused a concentration Ca-45(2+) efflux. A B-1 receptor agonist, d esArg(9)-bradykinin, also caused Ca-45(2+) efflux but with a potency s everal orders of magnitude lower than bradykinin. Curiously, several B -1 and B-2 receptor antagonists induced Ca-45(2+) efflux, indicating t hat this receptor may be coupled differently in CHO cells than in nati ve tissues. (C) 1998 Elsevier Science B.V.