The control of water flow across cell membranes is important for normal lung function, but the molecular mechanisms of water permeability at this level are incompletely defined. In January 22 Proceedings of the National Academy of Sciences, Landon King and colleagues from Johns Hopkins School of Medicine, Baltimore, show that aquaporins (AQP) are proteins that control the vascular permeability in the lung, and have a role in human pulmonary physiology.

King et al. intravenously injected 3 liters of saline into two unrelated AQP1-null individuals and five normal controls. They found that on high-resolution computed tomography scans control subjects had a 44% increase in the thickness of the airway wall, consistent with peribronchiolar edema formation; the airway wall thickness did not change in AQP1-null subjects. Both control and AQP1 null subjects showed approximately a 20% increase in pulmonary vessel area, suggesting similar degrees of volume loading (Proc Natl...