Endothelin-2 is a peptide vasoconstrictor and ligand for the endothelin (ET) receptors ETA and ETB (Kbs= 32.8 and 1.33 nM, respectively).1 It induces β-arrestin recruitment in CHO-K1 cells expressing human ETA and ETB (pD2s =8.75 and 8.55, respectively). Ex vivo, endothelin-2 induces vformal asoconstriction in isolated rat mesenteric arterial beds (ED50 = 90.8 pmol).2 Endothelin-2 also induces contraction of isolated rat uteri, an effect which is reversed by the ETA antagonist BQ-123 but not the ETB antagonist BQ-788 .3 Infusion of endothelin-2 restores vasoconstriction of vessels at the follicular apex of the ovarian follicle and ovulation in Amhr2cre/+Smo2 mice.