ABT-546 (A-216546) is a potent, highly selective and activeendothelinET_Areceptorantagonist with aK_iof 0.46 nM for [¹²⁵I]endothelin-1 binding to clonedhuman endothelinET_A. ABT-546 is >25,000-fold more selective for theET_Areceptorthan for theET_Breceptor. ABT-546 blocks endothelin-1-induced arachidonic acid release and phosphatidylinositol hydrolysis withIC₅₀of 0.59 nM and 3 nM, respectively^[1].

ABT-546 (A-216546) effectively inhibits specific I endothelin-1 binding to endothelin ET_Areceptor in membranes prepared from rat pituitary MMQ cells with an IC₅₀value of 0.56 nM. ABT-546 is much less effective in inhibiting specific [¹²⁵I]endothelin-3 binding to endothelin ET_Brceptor in membranes prepared from porcine cerebellum with an IC₅₀value of 16,700 nM. In membranes prepared from CHO cells stably transfected with the human endothelin ET_Aand ET_Breceptors, ABT-546 again effectively inhibits specific [¹²⁵I]endothelin-1 binding to endothelin ET_Areceptor with an IC₅₀value of 0.49 nM, but is less effective in inhibiting specific [¹²⁵I]endothelin-3 binding to endothelin ET_Breceptor with an IC₅₀value of 15,400 nM^[1].
In isolated vessels, ABT-546 inhibits endothelin ET_Areceptor-mediated endothelin-1-induced vasoconstriction, and endothelin ET_Breceptor-mediated sarafotoxin 6c-induces vasoconstriction with pA₂of 8.29 and 4.57, respectively^[1].

ABT-546 (A-216546; 0-100 mg/kg; oral administration; for 1 hour or 4 hours; male Sprague-Dawley rats) treatment dose-dependently blocks endothelin-1-induced pressor response in conscious rats^[1].

532.71

C₃₀H₄₈N₂O₆

212481-66-8

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