Notes: GRA Ex-25 is a glucagon receptor (GCGR) antagonist (IC50s = 55 and 56 nM for the human and rat receptors, respectively).{49499} It inhibits adenylate cyclase activity induced by glucagon (Item No. 24204) with a Ki value of 254 nM.{49500} GRA Ex-25 (3 mg/kg, i.v.) reduces glucagon-induced increases in blood glucose levels in rats.{49499}