Urotensin II is a peptide vasoconstrictor and agonist of the urotensin (UT) receptor (Ki= 2.06 nM for the human recombinant receptor expressed in HEK293 cells).1It stimulates intracellular calcium mobilization in HEK293 cells expressing human and rat UT (EC50s = 0.47 and 0.78 nM, respectively) but decreases intracellular calcium concentration in goby (G. mirabilis) enterocytes when used at a concentration of 500 nM.2Urotensin II (20 mU/ml) stimulates active sodium and chloride absorption across isolated goby posterior intestine in 5% seawater-adapted solution.3In vivo, urotensin II (1.5-150 nmol/kg) decreases diastolic blood pressure and increases heart rate in anesthetized rats.4It also reduces the pressor responses to sympathetic nerve stimulation, norepinephrine , and vasopressin in pithed rats when administered at a dose of 150 nmol/kg. 1.Ames, R.S., Sarau, H.M., Chambers, J.K., et al.Human urotensin-II is a potent vasoconstrictor and agonist for the orphan receptor GPR14Nature401(6750)282-286(1999) 2.Loretz, C.A., and Assad, J.A.Urotensin II lowers cytoplasmic free calcium concentration in goby enterocytes: Measurements using quin2Gen. Comp. Endocrinol.64(3)355-361(1986) 3.Loretz, C.A., Freel, R.W., and Bern, H.A.Specificity of response of intestinal ion transport systems to a pair of natural peptide hormone analogs: Somatostatin and urotensin IIGen. Comp. Endocrinol.52(2)198-206(1983) 4.Gibson, A., Wallace, P., and Bern, H.A.Cardiovascular effects of urotensin II in anesthetized and pithed ratsGen. Comp. Endocrinol.64(3)435-439(1986)

Urotensin II, mouse acetate (9047-55-6 free base) is an endogenous ligand for the orphan GPR14 or SENR. It is a potent vasoconstrictor.