– Urotensin I is, 41-aa neuropeptide, acts as an agonist of CRF receptor with pEC50s of 11.46, 9.36 and 9.85 for human CRF1, human CRF2 and rat CRF2α receptors in CHO cells, and Kis of 0.4, 1.8, and 5.7 nM for hCRF1, rCRF2α and mCRF2β receptors, respectively. Urotensin-I was first isolated from the urophysis of the white sucker, and has been shown to decrease blood pressure in the rat. UI consists of 41 aa residues with an amidated C-terminus.