Endothelin-2 (49-69), human (Human endothelin-2), is a 21-amino-acid vasoactive peptide that binds to G-protein-coupled receptors ET-RA and ET-RB.

At nanomolar concentrations, Endothelin-2 significantly induces strong and persistent vasoconstriction, similar to the effects observed with other endothelins (EC50=0.52 nM)[1]. It functions as a potent chemoattractant specifically for macrophages and THP-1 monocytic cells, but does not attract freshly isolated monocytes. The chemotactic activity towards Endothelin-2 demonstrates a characteristic bell-shaped curve. Research utilizing endothelin receptor antagonists has revealed that the ET-RB receptor mediates the directed cell migration towards Endothelin-2. Moreover, the presence of Endothelin-2 in tumor environments suggests it plays a role in modifying macrophage behavior, leading to the accumulation of activated macrophages in hypoxic regions.

Rats[1] For the assay of pressor activity, male Wistar rats weighing 300-350 g are anesthetized with urethane (1 g/kg i.p.) and pretreated with atropine (0.25 mg/kg i.v.), propranolol (1 mg/kg i.v.), and bunazocine (1 mg/kg i.v.). Additional maintenance doses (one-half of the initial doses) of the autonomic blockades are administered every 3-4 hr. Each animal is given only one bolus of Endothelin-2. 1 nM of Endothelin-2 in 50 渭L of buffer is bolus injected from a cannula inserted in the right femoral vein. The blood pressure is recorded from a cannula, which is placed in the right carotid artery and connected to a pressure transducer[1].