Abstract: UI (Urotensin I) or carp urotensin, obtained from Cyprinus carpio, has the formula: H-Asn-Asp-Asp-Pro-Pro-Ile-Ser-Ile-Asp-Leu-Thr-Phe-His-Leu-Leu-Arg-Asn-Met- Ile-Glu-Met-Ala-Arg-Asn-Glu-Asn-Gln-Arg-Glu-Gln-Ala-Gly-Leu-Asn-Arg-Lys-Tyr -Leu-Asp-Glu-Val-NH.sub.2. UI or a biologically active fragment thereof or a pharmaceutically acceptable salt of either, dispersed in a pharmaceutically acceptable liquid or solid carrier, can be administered to mammals to achieve a substantial elevation of ACTH, .beta.-endorphin, .beta.-lipotropin and corticosterone levels and/or a lowering of systemic blood pressure over an extended period of time.

Abstract: UI (Urotensin I) or white sucker urotensin, obtained from Catostomus commersoni, has the formula: H-Asn-Asp-Asp-Pro-Pro-Ile-Ser-Ile-Asp-Leu-Thr-Phe-His-Leu-Leu-Arg-Asn-Met- Ile-Glu-Met-Ala-Arg-Ile-Glu-Asn-Glu-Arg-Glu-Gln-Ala-Gly-Leu-Asn-Arg-Lys-Tyr -Leu-Asp-Glu-Val-NH.sub.2. Analogs have been synthesized that are at least as potent as UI, and UI or such an analog or a fragment of either or a pharmaceutically acceptable salts of any of the foregoing, dispersed in a pharmaceutically acceptable liquid or solid carrier, can be administered to mammals to achieve a substantial elevation of ACTH, .beta.-endorphin, .beta.-lipotropin and corticosterone levels and/or an increase in intestinal blood flow and/or a lowering of systemic blood pressure and/or a changing of regional blood distribution over an extended period of time.