Role of Endothelin-A (ETA) and Endothelin-B (ETB) Receptors in the Vasodilatory Response to Endothelin-3 (ET-3)

2014-08-27 03:14:40 | BioPortfolio


Endothelin-1 (ET-1) has been linked to a number of conditions including pulmonary arterial hypertension (PAH). ET-1 acts via 2 receptors, ETA and ETB. The ET-1 receptor blockers bosentan and sitaxsentan have been shown to be beneficial in patients with PAH. Bosentan blocks both ETA and ETB receptors. Sitaxsentan selectively blocks ETA receptors. Theoretically, selective ETA blockade may be associated with greater vasodilation and clearance of ET-1 by leaving the ETB receptor unblocked. This has not been directly studied in humans.

We aim to investigate the endothelial ETB-mediated vascular responses between bosentan and sitaxsentan by using a ETB selective agonist (ET-3). We hypothesise that at clinically relevant doses:

- Bosentan will show evidence of ETB receptor blockade compared to sitaxsentan and placebo.

- These effects will be confirmed by 2 functional markers of ETB receptor antagonism: plasma ET-1 (a very sensitive, but not necessarily clinically relevant marker), and the forearm vasodilator response to ET-3.

Study Design

Allocation: Randomized, Control: Placebo Control, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Caregiver, Investigator), Primary Purpose: Basic Science


Pulmonary Arterial Hypertension


Bosentan, Sitaxsentan, Placebo, Endothelin-3


Clinical Research Centre, Western General Hospital
United Kingdom


Active, not recruiting


University of Edinburgh

Results (where available)

View Results


Published on BioPortfolio: 2014-08-27T03:14:40-0400

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