Endothelin 1 (swine, human), AF 488-labeled is a synthetic Endothelin 1 peptide labled with AF 488. Endothelin 1 (swine, human) is a synthetic peptide with the sequence of human and swine Endothelin 1, which is a potent endogenous vasoconstrictor. Endothelin 1 acts through two types of receptors ET A and ET B.