The alveolar-capillary membrane serves as a barrier that prevents the accumulation of fluid in the alveolar space and restricts the diffusion of large solutes while facilitating an efficient gas exchange. When this barrier becomes dysfunctional, patients develop
acute lung injury (ALI), which is characterized by
pulmonary edema and increased
lung inflammation that leads to a life-threatening impairment of gas exchange. In addition to the increase of inflammatory
cytokines, plasma levels of
endothelin-1 (ET-1), which is a primarily endothelium-derived
vasoconstrictor, are increased in patients with ALI. As patients recover, ET-1 levels decrease, which suggests that ET-1 may not only be a marker of endothelial dysfunction but may have a role in the pathogenesis of ALI. While
pulmonary edema accumulates, alveolar fluid clearance (AFC) is of critical importance, as failure to return to normal clearance is associated with poor prognosis in patients with
pulmonary edema. AFC involves active transport mechanisms where
sodium (Na(+)) is actively transported from the alveolar airspaces, across the alveolar epithelium, and into the pulmonary circulation, which creates an osmotic gradient that is responsible for the clearance of lung
edema. In this article, we review the relevance of ET-1 in the development of ALI, not only as a
vasoconstrictor molecule but also by inhibiting AFC via the activation of endothelial ET-B receptors and generation. Furthermore, this review highlights the therapeutic role of drugs such as
beta-adrenergic agonists and, in particular, of
endothelin receptor antagonists in patients with ALI.