Potent α-adrenoceptor agonist that is at least 35-fold more potent at α1A than at α1B or α1D sites. Induces dose response increases in spontaneous Ca2+ transients in rat ventricular myocytes in vitro (EC50 = 6.9 nmol/L). Also available as part of the α1-Adrenoceptor Tocriset?. MW (observed): 390.29.