Endothelin-1 induces a strong pressor effect in ball pythons (Python regius).

Endothelin-1 (ET-1) is a very potent vasoactive peptide released from endothelial cells, and ET-1 plays an important role in the maintenance and regulation of blood pressure in mammals. ET-1 signaling is mediated by two receptors: ET and ET. In mammals, ET receptors are located on vascular smooth muscle where they mediate vasoconstriction.