Vasoconstrictive effects of endothelin-1, endothelin-3, and urotensin II in isolated perfused human lungs and isolated human pulmonary arteries

Background: Urotensin II (UII) has been identified as a ligand for the orphan receptor GPR14 through which it elicits potent vasoconstriction in humans and non-human primates. The pulmonary vasculature is particularly sensitive; human UII (hUII) exhibits a potency 28 times that of endothelin (ET)-1 in isolated pulmonary arteries obtained from cynomolgus monkeys. However, hUII induced vasoconstriction in isolated human intralobar pulmonary arteries is variable, possibly as a result of location dependent differences in receptor density or because it is only uncovered by disease dependent endothelial dysfunction. Methods: The vasoactivity of both hUII and gobi UII ( gUII) in comparison with ET-1 and ET-3 was studied in isolated perfused lung preparations (n = 14) and isolated intralobar pulmonary arteries ( n = 40, mean diameter 548 ( 27) mm) obtained from 17 men of mean ( SE) age 67 ( 2) years and eight women of mean ( SE) age 65 ( 3) years with a variety of vascular diseases. Results: ET-1 ( 10 pM - 100 nM) and ET-3 ( 10 pM - 30 nM) elicited vasoconstriction in the lung preparations, inducing comparable increases in pulmonary arterial pressure of 24.8 (4.5) mm Hg and 14.5 (4.9) mm Hg, respectively, at 30 nM ( p = 0.13). Similarly, ET-1 (10 pM - 300 nM) and ET-3 (10 pM-100 nM) caused marked vasoconstriction in isolated pulmonary arteries, inducing maximal changes in tension of 4.36 (0.26) mN/mm and 1.54 (0.44) mN/mm, respectively, generating -logEC(50) values of 7.67 (0.04) M and 8.08 (0.07) M, respectively (both p<0.05). However, neither hUII nor gUII (both 10 pM - 1 mu M) had any vasoactive effect in either preparation. Conclusion: UII does not induce vasoconstriction in isolated human pulmonary arterial or lung preparations and is therefore unlikely to be involved in the control of pulmonary vascular tone.