AMP-activated protein kinase (AMPK)-dependent and -independent pathways regulate hypoxic inhibition of transepithelial Na+ transport across human airway epithelial cells

作者：Tan C D; Smolenski R T; Harhun M I; Patel H K; Ahmed S G; Wanisch K; Yanez Munoz R J; Baines D L^*

来源：British Journal of Pharmacology, 2012, 167(2): 368-382.

DOI：10.1111/j.1476-5381.2012.01993.x

• AMPK
• ROS
• airway
• epithelium
• Na plus K plus ATPase
• ENaC

BACKGROUND AND PURPOSE Pulmonary transepithelial Na+ transport is reduced by hypoxia, but in the airway the regulatory mechanisms remain unclear. We investigated the role of AMPK and ROS in the hypoxic regulation of apical amiloride-sensitive Na+ channels and basolateral Na+K+ ATPase activity. EXPERIMENTAL APPROACH H441 human airway epithelial cells were used to examine the effects of hypoxia on Na+ transport, AMP : ATP ratio and AMPK activity. Lentiviral constructs were used to modify cellular AMPK abundance and activity; pharmacological agents were used to modify cellular ROS. KEY RESULTS AMPK was activated by exposure to 3% or 0.2% O2 for 60 min in cells grown in submerged culture or when fluid (0.1 mL.cm-2) was added to the apical surface of cells grown at the airliquid interface. Only 0.2% O2 activated AMPK in cells grown at the airliquid interface. AMPK activation was associated with elevation of cellular AMP : ATP ratio and activity of the upstream kinase LKB1. Hypoxia inhibited basolateral ouabain-sensitive Isc (Iouabain) and apical amiloride-sensitive Na+ conductance (GNa+). Modification of AMPK activity prevented the effect of hypoxia on Iouabain (Na+K+ ATPase) but not apical GNa+. Scavenging of superoxide and inhibition of NADPH oxidase prevented the effect of hypoxia on apical GNa+ (epithelial Na+ channels). CONCLUSIONS AND IMPLICATIONS Hypoxia activates AMPK-dependent and -independent pathways in airway epithelial cells. Importantly, these pathways differentially regulate apical Na+ channels and basolateral Na+K+ ATPase activity to decrease transepithelial Na+ transport. Luminal fluid potentiated the effect of hypoxia and activated AMPK, which could have important consequences in lung disease conditions.

• 出版日期2012-9