Mammalian pharmacology of the fish neuropeptide urotensin I.

The urophysis, a neurosecretory organ in fish, contains a number of putative hormones, collectively called urotensins. One of these, urotensin I--a straight chain peptide of 38 amino acids--produces a sustained hypotensive action in all mammalian species examined. In the anesthetized dog, the hypotensive action of native urotensin I is due to specific dilatation of the mesenteric vascular bed, the peptide having no significant actions on other vascular beds. Recent work has established that urotensin I is similar in structure to sauvagine and ovine corticotropin-releasing factor (CRF). Synthetic urotensin I and synthetic sauvagine both share the ability of synthetic ovine CRF to release adrenocorticotropin from cultured pituitary cells. All these synthetic peptides appear to lower blood pressure in the dog by the mechanism established for native urotensin I: selective mesenteric vasodilatation. The selectivity of the mesenteric vascular response suggests that a similar endogenous peptide might be the physiological regulator of gut blood flow. These peptides, or analogs, may also prove to be of value in ischemic bowel disease or anastomotic gastrointestinal surgery, or in reduction of afterload in heart failure.