Nebentan (YM598 free base) is a potent, selective and orally active non-peptide endothelin ET A receptor antagonist through the modification of Bosentan . Nebentan inhibits [ 125 I] endothelin-1 binding to cloned human endothelin ETA and ETB receptor, with K i of 0.697 nM and 569 nM, respectively YM598 can ameliorate the progression of cor pulmonale and myocardial infarction in vivo . In Vitro Nebentan inhibits the specific binding of [ 125 I] endothelin-1 to endothelin ET A and ET B receptors in a concentration dependent manner, K i values are 0.697 nM and 1.53 nM for human and rat endothelin ETA receptors, respectively. In contrast, YM598 exhibits low affinities for human and rat endothelin ET B receptors, with K i values of 569 nM and 155 nM,respectively. In measurement of intracellular Ca 2+ concentration, Nebentan concentration-dependently inhibits the increase in [Ca 2+ ]i induced by 10 nM endothelin-1 in both CHO cells and A10 cells, the IC 50 values are 26.2 nM for CHO cells and 26.7 nM for A10 cells, respectively. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Nebentan (oral administration; 0.1-1 mg/kg; 4 weeks) significantly inhibits the progression of pulmonary hypertension and the development of right ventricular hypertrophy. Nebentan (oral administration; 1 mg/kg; 30 weeks) significantly ameliorates the poor survival rate of CHF rats, it markedly reduces the hypertrophy of both ventricles as well as pulmonary congestion. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:ET A 0.697 nM (Ki) ET B 569 nM (Ki)