Adrenomedullin (13-52) is a truncated form of adrenomedullin (1-52) . It induces nitric oxide-dependent relaxation of and inhibits release of angiotensin II and endothelin-1 from isolated rat aorta. In vivo, adrenomedullin (13-52) decreases mean arterial pressure (MAP) in spontaneously and renal hypertensive rats in a dose-dependent manner. Adrenomedullin (13-52) (10-3,000 ng per animal) reverses increases in lobar arterial pressure induced by U-46619 in a dose-dependent manner in cats but has no effect on basal lobar arterial pressure or systemic arterial pressure. It also potentiates inflammatory edema and neutrophil accumulation in rats.