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.