RNA interference for alpha-ENaC inhibits rat lung fluid absorption in vivo.


RNA interference for alpha-ENaC inhibits rat lung fluid absorption in vivo.


Li Tianbo; Folkesson Hans G


American journal of physiology. Lung cellular and molecular physiology




We used siRNA against the alpha-ENaC (epithelial Na channel) subunit to investigate ENaC involvement in lung fluid absorption in rats by the impermeable tracer technique during baseline and after beta-adrenoceptor stimulation by terbutaline. Terbutaline stimulation of lung fluid absorption increased fluid absorption by 165% in pSi-0-pretreated rat lungs (irrelevant siRNA-generating plasmid). Terbutaline failed to increase lung fluid absorption in rats given the specific alpha-ENaC siRNA-generating plasmid (pSi-4). pSi-4 pretreatment reduced baseline lung fluid absorption by approximately 30%. alpha-ENaC was undetectable in pSi-4-pretreated lungs, regardless of condition but was normal in pSi-0-pretreated lungs. We carried out a dose-response analysis where rats were given 0-200 microg/kg body wt pSi-4, and alpha-ENaC mRNA and protein expressions were analyzed. To reach IC(50) for alpha-ENaC mRNA expression, 32 microg/kg body wt pSi-4 was needed, and to reach IC(50) for alpha-ENaC protein expression, 59 microg/kg body wt pSi-4 was needed. We tested for lung tissue specificity and found no changes in beta-ENaC expression, at either mRNA or protein level, as well as no changes in alpha(1)-Na-K-ATPase protein expression. We isolated alveolar epithelial type II cells 24 h after in vivo pSi-4 pretreatment. In these cells, alpha-ENaC mRNA was undetectable, demonstrating that alveolar epithelial ENaC expression was attenuated after intratracheal alpha-ENaC siRNA-generating plasmid DNA instillation. We tested for organ specificity and found no changes in kidney alpha- and beta-ENaC mRNA and protein expression. Thus we provide conclusive evidence that beta-adrenoceptor stimulation of lung fluid absorption is critically ENaC dependent, whereas baseline lung fluid absorption seemed less ENaC dependent.


Absorption/drug effects; Adrenergic beta-Agonists/pharmacology; Amiloride/pharmacology; Animals; Body Fluids/*metabolism; Capillary Permeability; Dose-Response Relationship; Drug; Endothelium; Epithelial Cells/metabolism; Epithelial Sodium Channels; Epithelium/metabolism; Inhibitory Concentration 50; Lung/enzymology/*metabolism; Male; Messenger/antagonists & inhibitors/metabolism; Permeability; Plasmids/administration & dosage/pharmacology; Rats; RNA; Small Interfering/genetics/pharmacology; Sodium Channels/drug effects/genetics/metabolism/*physiology; Sprague-Dawley; Terbutaline/pharmacology; Tissue Distribution; Vascular/metabolism


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Li Tianbo; Folkesson Hans G, “RNA interference for alpha-ENaC inhibits rat lung fluid absorption in vivo.,” NEOMED Bibliography Database, accessed March 3, 2024, https://neomed.omeka.net/items/show/4628.