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.

In vitro, bosentan has been shown to improve human endothelial cell and reduce neointimal and smooth muscle proliferation[3].

In pigs in vivo, bosentan has been shown to partially restore hypoxia-induced reductions in nitric oxide[3].

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)