Adrenomedullin: Potential in physiology and pathophysiology

Adrenomedullin (ADM), a 52-amino acid ringed-structure peptide with C-termi nal amidation, was originally isolated from human pheochromocytoma. ADM med iates vasodilatory and natriuretic properties through the second messenger cyclic adenosine 3',5'-monophosphate (cAMP), nitric oxide and the renal pro staglandin system. ADM immunoreactivity and its gene are widely distributed in cardiovascular, pulmonary, renal, gastrointestinal, cerebral and endocr ine tissues. ADM is also synthesized and secreted from vascular endothelial and smooth muscle cells. When injected intravenously, ADM increases flow r ates predominantly in organs in which the ADM gene is highly expressed, sug gesting that ADM acts as a local autocrine and/or paracrine vasoactive horm one. In addition, ADM is a circulating hormone and its plasma concentration is increased in various cardiorenal diseases such as hypertension, chronic renal failure and congestive heart failure. Current evidence suggests that ADM plays an important role in fluid and electrolyte homeostasis and cardi orenal regulation, however further investigations are required to address t he importance of ADM under various physiological and pathophysiological con ditions.