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.

Adrenomedullin (22-52) is a C-terminal fragment of adrenomedullin (1-52) . In vitro, adrenomedullin (22-52) reduces basal corticosterone production in a mixture of rat adrenocortical and adrenomedulllary cells. It also reverses increases in ACTH-stimulated corticosterone production induced by adrenomedullin (1-52). Adrenomedulin (22-52) (0.5 and 5 μg/kg/min) has no effect on basal regional cerebral blood flow but reverses increases in regional cerebral blood flow induced by rat adrenomedullin in rats. Unlike adrenomedullin (1-52), adrenomedullin (22-52) has no effect on mesenteric arterial perfusion pressure in cats.