Adrenomedullin: a novel cardiovascular regulatory peptide

In 1993, a Japanese group reported the occurrence of a potent vasodilator peptide in acid extracts of a human phaeochromocytoma, using the activity of rat platelet cAMP activity as a biological assay, followed by HPLC purification and amino acid sequencing. The peptide consisted of 52 amino acids, had one intramolecular disulphide bond and an amidated C-terminal tyrosine, and was named adrenomedullin (AM). When AM was injected intravenously (3 nmol/kg) into rats, it resulted in a fall in blood pressure, lasting for 30-60 min. This was comparable to the hypotensive activity of calcitonin gene-related peptide (CGRP) (which is established as one of the strongest vasodilators). These findings led to the conclusion that AM is a potent and long-acting hypotensive peptide, with a putative role in blood pressure control.