A: levels of ET-1 in culture media of control (open bars) and BMPR2 mutant BMDM (solid bars) following LPS stimulation for 4 and 24 h. At baseline, low levels of ET-1 were present in culture media of control and BMPR2 mutant BMDM. These levels increased significantly on activation with LPS (#P < 0.001). Levels of ET-1 were significantly greater in culture media of activated mutant BMDM compared with controls (*P < 0.05). Data are expressed as means ± SE; n = 12. B: levels of ET-1 in culture media of control BMDM in the presence of ETA and ETB antagonist (BQ-123 and BQ-788, respectively) at baseline and following LPS stimulation for 4 h. Open bars, no ET-1 receptor antagonists; rightward diagonal bars, presence of ETA antagonist; leftward diagonal bars, presence of ETB antagonist; solid bars, both ET-1 receptor antagonists. At baseline, ETA and ETB receptor antagonists did not affect levels of ET-1 in culture media. On activation with LPS, levels of ET-1 were significantly higher in culture media of BMDM treated with ETB receptor antagonist (*P < 0.05) as well as with both ETA and ETB receptor antagonists (#P < 0.001). Data are expressed as means ± SE, n = 9.