| Description: |
Ambrisentan is a selective ET type A receptor (ETAR) antagonist. |
| In Vivo: |
In the Ambrisentan group, hepatic hydroxyproline content is significantly lower than in the control group (18.0 μg/g±6.1 μg/g vs 33.9 μg/g±13.5 μg/g liver, respectively, P=0.014). Hepatic fibrosis estimated by Sirius red staining and areas positive for α-smooth muscle actin, indicative of activated hepatic stellate cells, are also significantly lower in the Ambrisentan group (0.46%±0.18% vs 1.11%±0.28%, respectively, P=0.0003; and 0.12%±0.08% vs 0.25%±0.11%, respectively, P=0.047). Moreover, hepatic RNA expression levels of procollagen-1 and tissue inhibitor of metalloproteinase-1 (TIMP-1) are significantly lower by 60% and 45%, respectively, in the Ambrisentan group. Inflammation, steatosis, and endothelin-related mRNA expression in the liver are not significantly different between the groups. Ambrisentan attenuates the progression of hepatic fibrosis by inhibiting hepatic stellate cell activation and reducing procollagen-1 and TIMP-1 gene expression. Ambrisentan did not affect inflammation or steatosis[1]. |
| In Vitro: |
Ambrisentan is an endothelin type A receptor antagonist[1]. Ambrisentan induces Nrf2 activation. Endothelial permeability increased in BMEC monolayers at 24 h of hypoxia exposure and compared to vehicle control, Ambrisentan attenuates hypoxia-induced BMEC leak. These results are reversed when prior to treatment BMEC are transfected with siRNA against Nrf2[2]. |
| Cell Assay: |
Unless otherwise stated, for each BMEC experiment cells are randomly divided into 4 groups: (1) normoxia vehicle control (Nx-CTRL); (2) normoxia-treated; (3) hypoxia (24 h) control (Hx-CTRL) and (4) hypoxia (24 h) treated. As previously described, Nrf2 activators are added 24 h prior to any hypoxic exposures. Cell treatments are; Protandim (100 μg/mL), methazolamide (125 μg/mL, nifedipine (7 μg/mL) or Ambrisentan (40 μg/mL). In addition, some cells are treated with Nrf2 siRNA. In these experiments, siRNA is added 24 h prior to drug treatments. The rationale for 24 h hypoxia exposure for BMEC is to ensure that cells remained transfected with siRNA for the pre-treatment of drugs (24 h in normoxia) and during the 24 h hypoxia exposure. Data is collected from at least three separate cell culture preparations on three separate days (n=9)[2]. |
| Animal Administration: |
Unless otherwise stated, for each BMEC experiment cells are randomly divided into 4 groups: (1) normoxia vehicle control (Nx-CTRL); (2) normoxia-treated; (3) hypoxia (24 h) control (Hx-CTRL) and (4) hypoxia (24 h) treated. As previously described, Nrf2 activators are added 24 h prior to any hypoxic exposures. Cell treatments are; Protandim (100 μg/mL), methazolamide (125 μg/mL, nifedipine (7 μg/mL) or Ambrisentan (40 μg/mL). In addition, some cells are treated with Nrf2 siRNA. In these experiments, siRNA is added 24 h prior to drug treatments. The rationale for 24 h hypoxia exposure for BMEC is to ensure that cells remained transfected with siRNA for the pre-treatment of drugs (24 h in normoxia) and during the 24 h hypoxia exposure. Data is collected from at least three separate cell culture preparations on three separate days (n=9)[2]. |
| References: |
Unless otherwise stated, for each BMEC experiment cells are randomly divided into 4 groups: (1) normoxia vehicle control (Nx-CTRL); (2) normoxia-treated; (3) hypoxia (24 h) control (Hx-CTRL) and (4) hypoxia (24 h) treated. As previously described, Nrf2 activators are added 24 h prior to any hypoxic exposures. Cell treatments are; Protandim (100 μg/mL), methazolamide (125 μg/mL, nifedipine (7 μg/mL) or Ambrisentan (40 μg/mL). In addition, some cells are treated with Nrf2 siRNA. In these experiments, siRNA is added 24 h prior to drug treatments. The rationale for 24 h hypoxia exposure for BMEC is to ensure that cells remained transfected with siRNA for the pre-treatment of drugs (24 h in normoxia) and during the 24 h hypoxia exposure. Data is collected from at least three separate cell culture preparations on three separate days (n=9)[2]. |
