Regulation of fluid secretion. Stimulates primary urine secretion by Malpighian tubules and causes a dose-dependent stimulation of cAMP levels in the tubules. Has a greater effect on the transport of Na(+) then K(+) ions. In vitro, has synergistic effects with the smaller diuretic hormone DH(31) which co-occurs with it. Belongs to the sauvagine/corticotropin-releasing factor/urotensin I family.