OBJECTIVETo explore the association of epithelial sodium channel alpha subunit (alphaENaC) with terbutaline-induced transient enhancement of pulmonary edema clearance in adult rats with acute lung injury (ALI).

METHODSThe effect of 1-h intratracheal terbutaline treatment on pulmonary edema clearance in adult rats with experimental ALI was observed by blood gas analysis, lung tissue HE staining, and extravascular lung water (EVLW) content measurement. The mRNA and protein expressions of alphaENaC in the lung tissues were detected by fluorescence quantitative real-time RT-PCR and Western blotting, respectively.

RESULTTerbutaline treatment of the rats with ALI resulted in significant differences in PaO2, oxygenation index, and EVLW from those in ALI group without treatment. No significant differences in pulmonary alphaENaC mRNA and protein expressions were noted between the normal control, ALI, and terbutaline-treated ALI groups.

CONCLUSIONSIntratracheal terbutaline administration for 1 h can significantly promote pulmonary edema clearance in adult rats with ALI, and this effect is not mediated by alphaENaC gene expression.

Acute Lung Injury ; chemically induced ; complications ; drug therapy ; genetics ; metabolism ; Animals ; Epithelial Sodium Channels ; genetics ; metabolism ; Female ; Male ; Oleic Acid ; Pulmonary Edema ; drug therapy ; etiology ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Terbutaline ; therapeutic use

BACKGROUNDAcute lung injury (ALI) is a common complication of sepsis that is associated with high mortality. Intracellular Ca2+ overload plays an important role in the pathophysiology of sepsis-induced ALI, and cyclic adenosine diphosphate ribose (cADPR) is an important regulator of intracellular Ca2+ mobilization. The cluster of differentiation 38 (CD38)/cADPR pathway has been found to play roles in multiple inflammatory processes but its role in sepsis-induced ALI is still unknown. This study aimed to investigate whether the CD38/cADPR signaling pathway is activated in sepsis-induced ALI and whether blocking cADPR-mediated calcium overload attenuates ALI.

METHODSSeptic rat models were established by cecal ligation and puncture (CLP). Rats were divided into the sham group, the CLP group, and the CLP+ 8-bromo-cyclic adenosine diphosphate ribose (8-Br-cADPR) group. Nicotinamide adenine dinucleotide (NAD+), cADPR, CD38, and intracellular Ca2+ levels in the lung tissues were measured at 6, 12, 24, and 48 h after CLP surgery. Lung histologic injury, tumor necrosis factor (TNF)-μ, malondialdehyde (MDA) levels, and superoxide dismutase (SOD) activities were measured.

RESULTSNAD+, cADPR, CD38, and intracellular Ca2+ levels in the lungs of septic rats increased significantly at 24 h after CLP surgery. Treatment with 8-Br-cADPR, a specific inhibitor of cADPR, significantly reduced intracellular Ca2+ levels (P = 0.007), attenuated lung histological injury (P = 0.023), reduced TNF-μ and MDA levels (P < 0.001 and P = 0.002, respectively) and recovered SOD activity (P = 0.031) in the lungs of septic rats.

CONCLUSIONSThe CD38/cADPR pathway is activated in the lungs of septic rats, and blocking cADPR-mediated calcium overload with 8-Br-cADPR protects against sepsis-induced ALI.

ADP-ribosyl Cyclase 1 ; metabolism ; Acute Lung Injury ; chemically induced ; drug therapy ; Animals ; Calcium ; metabolism ; Cyclic ADP-Ribose ; analogs & derivatives ; antagonists & inhibitors ; metabolism ; therapeutic use ; Male ; Malondialdehyde ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sepsis ; complications ; Superoxide Dismutase ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism

Reactive oxygen species (ROS) play a crucial role in acute lung injury. Tissue inflammation, the increased vascular permeability, and plasma exudation are cardinal features of acute lung injury. Angiopoietin-1 (Ang1) has potential therapeutic applications in preventing vascular leakage and also has beneficial effects in several inflammatory disorders. Recently developed COMP-Ang1 is more potent than native Ang1 in phosphorylating tyrosine kinase with immunoglobulin and EGF homology domain 2 receptor in endothelial cells. However, there are no data on effects and related molecular mechanisms of COMP- Ang1 on ROS-induced acute lung injury. We used hydrogen peroxide (H2O2)-inhaled mice to evaluate the effect of COMP-Ang1 on pulmonary inflammation, bronchial hyper-responsiveness, and vascular leakage in acute lung injury. The results have revealed that VEGF expression, the levels of IL-4, TNF-alpha, IL-1 beta, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 in lungs, the levels of hypoxia-inducible factor-1alpha (HIF-1 alpha) and NF-kappa B in nuclear protein extracts, phosphorylation of Akt, and vascular permeability were increased after inhalation of H2O2 and that the administration of COMP-Ang1 markedly reduced airway hyper-responsiveness, pulmonary inflammation, plasma extravasation, and the increases of cytokines, adhesion molecules, and VEGF in lungs treated with H2O2. We have also found that the activation of HIF-1a and NF-kappa B and the increase of phosphoinositide 3-kinase activity in lung tissues after H2O2 inhalation were decreased by the administration of COMP-Ang1. These results suggest that COMP-Ang1 ameliorates ROS-induced acute lung injury through attenuating vascular leakage and modulating inflammatory mediators.
Acute Lung Injury/chemically induced/complications/*drug therapy/metabolism ; Administration, Inhalation ; Airway Resistance/drug effects ; Animals ; Bronchial Hyperreactivity/drug therapy/etiology ; Bronchoalveolar Lavage Fluid ; Capillary Permeability/*drug effects ; Cytokines/antagonists & inhibitors ; Female ; Hydrogen Peroxide/adverse effects ; Hypoxia-Inducible Factor 1, alpha Subunit/antagonists & inhibitors ; Intercellular Adhesion Molecule-1/metabolism ; Mice ; Mice, Inbred BALB C ; NF-kappa B/antagonists & inhibitors ; Pneumonia/*drug therapy/etiology ; Recombinant Fusion Proteins/*administration & dosage ; Vascular Cell Adhesion Molecule-1/metabolism