Bosentan (Benzenesulfonamide) is a sulfonamide-derived, competitive and specific endothelin receptor antagonist with a slightly higher affinity for the endothelin A receptor than endothelin B receptor. Bosentan blocks the action of endothelin 1, an extremely potent endogenous vasoconstrictor and bronchoconstrictor, by binding to endothelin A and endothelin B receptors in the endothelium and vascular smooth muscle. Bosentan decreases both pulmonary and systemic vascular resistance and is particularly used in the treatment of pulmonary arterial hypertension.

ETB:95 nM(Ki), ETA:4.7 nM(Ki)

Incubation solutions containing bosentan (1, 10 and 100 µM) are prepared in cell culture medium. On the sixth day of culturing of the sandwich-cultured hepatocytes, cell culture medium is removed from the wells and incubation solution containing bosentan is added to the cells. The cells were incubated with the solution for 24 h at 37°C. After the exposure, the incubation solution id removed and the cells are rinsed with Plus (+) or Minus (−) buffer. The buffer solution is then removed and the cells are incubated with fresh Plus (+) or Minus (−) buffer for 5 min at 37°C. Following this 5 minute incubation, the buffer solution is collected and any remaining buffer is removed. The cells are then washed three times with ice-cold Plus (+) buffer and the plates are frozen at −80°C until processed for bioanalysis. (Only for Reference)