Pharmacology of the human CGRP1 receptor in Cos 7 cells.

Only limited pharmacological characterization of the CGRP1 receptor, a heterodimer of the calcitonin (CT) receptor-like receptor (CL) and receptor activity-modifying protein 1 has been performed in cells that do not endogenously express RAMP2. We characterized the receptor in RAMP-deficient Cos 7 cells by measuring cAMP responses following agonist treatment in the absence or presence of antagonists. Potent cAMP responses to human alpha-and beta-CGRP (Cys(Et)2,7)halphaCGRP and human adrenomedullin (AM) were observed. Adrenomedullin15-52 was also an effective agonist of the CGRP1 receptor but human and salmon calcitonin and rat amylin were only weak agonists. As expected, BIBN4096BS and CGRP(8-37) were effective antagonists of the CGRP1 receptor. (Cys(Acm)2,7)halphaCGRP also antagonized CGRP responses. Antagonists of related receptors were only weakly able to inhibit CGRP responses.