Endothelin-2 (49-69), human (Endothelin-2 (human, canine)) is a 21-amino acid vasoactive peptide that binds to G-protein-linked transmembrane receptors, ET-RA and ET-RB. In Vitro: At nanomolar concentrations, Endothelin-2 exhibits a strong and long-lasting vasoconstrictor activity characteristic of endothelin (EC₅₀=0.52 nM)^[1].
Endothelin-2 is a chemoattractant for macrophages and THP-1 monocytic cells, but not for freshly isolated monocytes. The chemotactic response to Endothelin-2 shows a typical bell-shaped response curve. Experiments with endothelin receptor antagonists shows that migration to Endothelin-2 is mediated via the ET-RB receptor. Endothelin-2 expression by tumors may modulate the behavior of macrophages such that activated cells accumulate in areas of hypoxia^[2]. In Vivo: Two distinct phases of pressor effects are typically seen in response to Endothelin-2: the early phase immediately follows the depressor response and dominates during the next 3-10 min, whereas the late pressor effect develops 10-20 min after the injection and lasts >1 hr^[1].