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Am J Respir Crit Care Med. 2009 Jan 15;179(2):113-22. doi: 10.1164/rccm.200804-540OC. Epub 2008 Oct 23.

Endothelin-1 impairs alveolar epithelial function via endothelial ETB receptor.

Author information

1
Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA. alejandro-comellas@uiowa.edu

Abstract

RATIONALE:

Endothelin-1 (ET-1) is increased in patients with high-altitude pulmonary edema and acute respiratory distress syndrome, and these patients have decreased alveolar fluid reabsorption (AFR).

OBJECTIVES:

To determine whether ET-1 impairs AFR via activation of endothelial cells and nitric oxide (NO) generation.

METHODS:

Isolated perfused rat lung, transgenic rats deficient in ETB receptors, coincubation of lung human microvascular endothelial cells (HMVEC-L) with rat alveolar epithelial type II cells or A549 cells, ouabain-sensitive 86Rb+ uptake.

MEASUREMENTS AND MAIN RESULTS:

The ET-1-induced decrease in AFR was prevented by blocking the endothelin receptor ETB, but not ETA. Endothelial-epithelial cell interaction is required, as direct exposure of alveolar epithelial cells (AECs) to ET-1 did not affect Na,K-ATPase function or protein abundance at the plasma membrane, whereas coincubation of HMVEC-L and AECs with ET-1 decreased Na,K-ATPase activity and protein abundance at the plasma membrane. Exposing transgenic rats deficient in ETB receptors in the pulmonary vasculature (ET-B(-/-)) to ET-1 did not decrease AFR or Na,K-ATPase protein abundance at the plasma membrane of AECs. Exposing HMVEC-L to ET-1 led to increased NO, and the ET-1-induced down-regulation of Na,K-ATPase was prevented by the NO synthase inhibitor l-NAME, but not by a guanylate cyclase inhibitor.

CONCLUSIONS:

We provide the first evidence that ET-1, via an endothelial-epithelial interaction, leads to decreased AFR by a mechanism involving activation of endothelial ETB receptors and NO generation leading to alveolar epithelial Na,K-ATPase down-regulation in a cGMP-independent manner.

PMID:
18948426
PMCID:
PMC2633058
DOI:
10.1164/rccm.200804-540OC
[Indexed for MEDLINE]
Free PMC Article

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