Effect of inhaled nitric oxide on aquaporin expression in newborn rat lung in acute hyperoxic lung injury

AIM:To investigate the effect of inhaled nitric oxide on aquaporin expression and alveolar epithelial fluid transport in newborn rats with acute hyperoxic lung injury. METHODS:32 newborn SD rats were randomized to breathe for 48 h room air (C), >95%O₂ (O), >95%O₂+10^-5 NO (NO only in the first 24 h, ONO), room air + NO (CN). Then, the rats were killed, the lung wet-to-dry weight ratio (Q_W/Q_D), the histology, and AQP1, AQP5, α₁-NKA, α-ENaC mRNA expressions in the lungs were measured. RESULTS:Compared with C group, the Q_W/Q_D in O group significantly increased (P<0.01), and AQP1 mRNA expression decreased significantly (P<0.01). Compared with O group, ONO group had a lower level of Q_W/Q_D (P<0.05), and AQP1 mRNA expression increased (P<0.05). AQP5 mRNA expression in all groups remained unchanged. CONCLUSION:In newborn rats with acute hyperoxic lung injury, inhaled 10-5 nitric oxide for 24 h may attenuate lung edema and increase AQP1 mRNA expression, suggesting that inhaled 10^-5 nitric oxide for 24 h may promote the AQP1 expression in lung in this model of acute lung injury.     

Changes of aquaporin expression in blood-brain barrier induced by glioma cells

AIM:To investigate the effects of glioma cells on aquaporin expression in blood-brain barrier and their importance in pathophysiology.METHODS:A blood-brain barrier model was established by coculture of ECV304 and astrocytesin vitro. HPLC was used to determine the change of water transport ofin vitroblood-brain barrier model after the influence of glioma cells. The expression levels of AQP1 and AQP4 were analyzed by semiquatitative RT-PCR.RESULTS:Glioma cells decreased expression level of AQP4 of astrocytes and induced abnormal expression of aquaporin-1 in endothelial cell line. The water transport ofin vitroblood-brain barrier model from luminal side to abluminal side was increased after coculture with glioma cells.CONCLUSION:The vasogenic brain edema induced by glioma cells may not be the result of hyperpermeability of blood-brain barrier to macromolecules in plasma. The changes of aquaporin expression may be the molecular basis of brain edema induced by glioma cells.     

Effect of aquaporin 4 on lymphatic brain edema in rats

AIM：To investigate the role of aquaporin 4 (AQP4) in the formation and elimination of lymphatic brain edema (LBE). METHODS：Sprague-Dawley rats were randomly divided into sham group and LBE group. LBE was induced by ligating bilateral cervical lymphatic tubes and removing the corresponding lymphatic nodes. The water contents in the cerebral cortex were measured by wet-dry weight method. The expression of AQP4 in the cerebral cortex was detected 1 d, 3 d, 7 d, 11 d and 15 d after a cervical lymphatic blockade or a sham operation by immunohistofluorescence staining and Western blotting. Furthermore, correlation analysis was made between the protein expression of AQP4 and the brain water content. RESULTS：Compared with sham group, cerebral water content, and the protein expression of AQP4 in the LBE rats increased significantly 3 d after operation, peaked at 7 d, followed by gradually stepping down. Furthermore, the expression of AQP4 was positively correlated with brain water content (r=0.8024, P<0.05). CONCLUSION：AQP4 may play an important role in the formation and elimination of LBE.     

Chronic alcohol abuse and acute lung injury/acute respiratory distress syndrome

ecent studies have shown that chronic alcohol abuse is associated with excessive morbidity and mortality in critically sick patients, and is an independent risk factor for non-cardiac diseases to develop acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Chronic alcohol abuse damages pulmonary vascular endothelial cells and alveolar epithelial cells through a variety of mechanisms, which results in increase of the alveolar-capillary permeability and extra vascular lung water level. Clinicians should pay attention to this phenomenon and further studies should be explored to identify the mechanisms involved in the predisposition to ALI/ARDS. Application of angiotensin receptor antagonist, recombinant granulocyte/macrophage colony stimulating factor, glutathione precursors and zinc supplementation may be useful to prevent and treat the patient who is a chronic alcohol abuser and at high risk of suffering from ALI/ARDS.     

Effects of 5-lipoxygenase inhibitor zileuton on destruction of blood-brain barrier permeability induced by focal cerebral ischemia-reperfusion injury in rats

AIM: To investigate the influential factors of the blood-brain barrier (BBB) permeability and to observe the effects of zileuton, a selective 5-lipoxygenase inhibitor (5-LO), on focal cerebral ischemia-reperfusion injury (CIRI).METHODS: The right middle cerebral artery of the rat was occluded by inserting a thread through internal carotid artery for 2 h, and then reperfused for 24 h. Zileuton (10, 50 mg·kg-1, po) was orally administered 2 h before ischemia and at 0, 5, 10 h after reperfusion. The permeability of blood brain barrier (BBB) was detected by using Evans blue (EB) as a labelling compound. The degree of cerebral edema was estimated by AutoCAD image analysis software. The mRNA of cysteiny leukotrienes receptor1 (CysLTR1) was detected by RT-PCR. The content of LTB4 in serum was measured by enzyme linked immunosorbent assay (ELISA). The expressions of AQP4 and MMP-9 proteins were measured by immunohistochemical staining method. RESULTS: After middle cerebral artery occlussion 2 h/reperfusion 24 h, the permeability of BBB in the brain tissue of injured side and the brain edema degree were increased. The content of LTB4 in serum was elevated. The expression of CysLTR1 mRNA from the brain tissue of occluded side was enhanced. The expressions of MMP-9 and AQP4 proteins of the ischemia realm and ischemia penumbra (IP) of the infarct focus perimeter were increased. Both 10 and 50 mg·kg-1 doses of zileuton dramatically relieved the BBB permeability destruction and the degree of the brain edema, inhibited the expression of CysLTR1 mRNA in the brain tissue and also reduced the content of LTB4 in serum. The expressions of AQP4 and MMP-9 proteins in the brain tissue were also decreased.CONCLUSION: The permeability of BBB is destroyed after the focal CIRI. The mechanisms of protective effect of zileuton might be attributed to its effects by inhibiting the activation of 5-LO pathways on the brain tissue and circulatory blood, reducing the expressions of AQP4 and MMP-9 proteins of the ischemia and IP realm in the brain tissue.     

Alteration of AQP2 expression in kidney tissues of emphysema model rats

AIM: To observe the expressions of aquaporin 2 (AQP2) in kidney tissues and the contents of endotoxin (ET), interleukin-1 β (IL-1β), tumor necrosis factor-α (TNF-α) in serum in emphysema model rats, and to investigate the relationship between lungs and kidney in humoral metabolism. METHODS: The rats of emphysema were treated by injecting lipopolysaccharide into the trachea with cigarette smoking. Immunohistochemistry and Western blotting analysis were used to observe the expression of AQP2 in kidney tissues. RT-PCR was applied to detect the expression of AQP2 mRNA in kidney tissues. Blood sample and lung tissue were taken and the levels of ET, IL-1β and TNF-α were measured by radioimmunoassay. RESULTS: AQP2 expression in the kidney tissue in model group was greater than that in control group, and the expression of AQP2 mRNA showed the same results (P<0.01). ET, IL-1β and TNF-α levels in serum and lung tissue in model group were markedly higher than those in control group (P<0.01). CONCLUSION: In the emphysema model rats, AQP2 expression is up-regulated in the kidney tissue. The mechanism of emphysema may be related to increasing the levels of ET, IL-1β and TNF-α in the serum and lung tissue obviously.     

Effects of ghrelin on brain edema and aquaporin 4 expression after cerebral ischemia/reperfusion in rats

AIM: To explore the effects of ghrelin on the brain edema, the permeability of blood-brain barrier (BBB) and the expression of aquaporin 4 (AQP4) after cerebral ischemia/reperfusion in rats. METHODS: Adult male Sprague-Dawley rats were randomly divided into sham operation group, middle cerebral artery occlusion (MCAO) group and ghrelin treatment group. The MCAO model was made with nylon thread for 2 h of occlusion following 22 h of reperfusion. Ghrelin at a dose of 10 nmol/kg was injected via femoral vein at the beginning of reperfusion. The cerebral infarct volume was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Brain functional deficits were evaluated by determining the neurological scores. The changes of brain swelling and water content were analyzed through volume calculation and dry/wet weight measurement. The permeability of BBB was detected by collecting extravascular Evans blue (EB) in the brain cortex. The changes of AQP4 expression were assessed by the methods of immunohistochemistry and Western blotting. RESULTS: Compared with MCAO group, the rats in ghrelin treatment group had smaller brain infarct volume, lower EB exudation content and neurological scores. The percentage of brain swelling, water content and AQP4 expression were lower in ghrelin treatment group than those in MCAO group. CONCLUSION: Ghrelin reduces the injury of cerebral ischemia/reperfusion, and lightens the brain edema and BBB damage in rats. Ghrelin also inhibits the expression of AQP4 in brain tissue.     

利用远缘杂交创制抗虫长豇豆新种质

开展了长豇豆（Vigna unguiculata L. ssp. sesquipedalis）与其近缘种饭豆[V. umbellata（Thunb.）Ohwi & Ohashi]的远缘杂交，对亲本和杂交高世代（F7）进行了田间抗虫水平和荚果性状观测鉴定。结果表明：（1）饭豆品种的田间抗虫水平普遍高于长豇豆品种；（2）在长豇豆和饭豆远缘杂交的全分离谱世代（F6）363 个株系中，初选了 41 个虫害发生较轻的单株，组成 F7 代供后续鉴定；（3）田间试验观测到 F7 代株系抗虫水平有较大分离，复选出 7 个高抗水平的重组株系；结合单荚质量、荚长和籽粒密度等荚果相关性状数据特征，决选出在营养生长期对斜纹夜蛾、甜菜夜蛾等主要害虫综合抗性达到高抗（HR）水平且荚果性状近似于长豇豆的株系 2 个，实现了长豇豆抗虫的种质创新。     

Upregulation of neurokinin A levels by nerve growth factor in the experimental asthmatic guinea pig

AIM: To explore the regulatory mechanism of nerve growth factor (NGF) on neurokinin A in the experimental asthmatic guinea pig. METHODS: Radioimmunoassay was used to determine the alteration of neurokinin A levels in the lower respiratory tract and visceral sensory afferent sites while NGF was absent (inhalation of NGF antibody through nasal cavity) in the asthmatic guinea pig. RESULTS: The contents of neurokinin A in the trachea, bronchus, lung, C₇-T₅ spinal ganglia and the correspondent spinal dorsal horn, nodose ganglia and solitary nucleus area in the experimental asthmatic guinea pig with the absent of NGF in the respiratory tract were much lower than those in the asthmatic and control groups (P＜0.01). CONCLUSION: NGF upregulated the contents of neurokinin A in the lower respiratory tract and visceral sensory sites of the experimental asthmatic guinea pig, and both might be involved in the pathogenesis of asthma.     

Up-regulatory effect of nerve growth factor on substance P in the experimental asthma

AIM: To explore the regulatory mechanism of nerve growth factor (NGF) on substance P in the experimental asthmatic guinea pig. METHODS: Radioimmunoassay was used to determine the alteration of substance P levels in the lower respiratory tract and visceral sensory afferent sites while NGF was absent (inhalation of NGF antibody through nasal cavity) in the asthmatic guinea pig. RESULTS: The contents of substance P in the trachea, bronchus, lung, C7-T5 spinal ganglia and the correspondent spinal dorsal horn, nodose ganglia and solitary nucleus area in the experimental asthmatic guinea pig with the absent of NGF in the respiratory tract, were much lower than those in the asthmatic and control groups (P<0.01). CONCLUSION: NGF upregulates the contents of substance P in the lower respiratory tract and visceral sensory sites of the experimental asthmatic guinea pig, which might be involved in the pathogenesis of asthma.     

Effect of edaravone on expression of Aβ and AQP4 and activity of MMP2 and MMP9 in acute cerebral ischemia/reperfusion rats

AIM: To investigate the effect of edaravone on acute cerebral ischemia/reperfusion rats. METHODS: SD rats were randomly divided into sham operation group (saline), model group (modeling given saline), low dose group (edaravone at 6 mg/kg) and high dose group (edaravone at 10 mg/kg). The rat model was established by Zea Longa suture method. The nerve function scores were evaluated after operation, and the infarct volume was measured by TTC assay. The mRNA expression of aquaporin 4 (AQP4) and amyloid β-protein (Aβ) in the brain tissue was detected by RT-qPCR. The protein levels of APQ4 and Aβ were determined by Western blot. The activity of matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9(MMP9) was detected by gelatin zymography. RESULTS: Compared with model group, edaravone administration markedly alleviated neurological deficits, histological damages and brain edema. The mRNA and protein levels of AQP4 and Aβ, and the activity of MMP2 and MMP9 were downregulated (P<0.05). Furthermore, the improvements in high dose group were significantly more effective than those in low dose group. CONCLUSION: Edaravone significantly reduces neurological deficits and brain edema in the rats with acute ischemic stroke, and the mechanisms may be related to the downregulation of AQP4 and Aβ, and the activation of MMP2 and MMP9.     

Effects of chlorine gas exposure on lung haemodynamic and respiratory function in intact and isolated perfused rabbit lungs

AIM:To investigate the effect of high concentration of chlorine gas(Cl₂) exposure on lung haemodynamic and respiratory function in intact and isolated perfused rabbit lungs (IPLs). METHODS:8 intact and 10 IPLs were exposed to Cl₂ at high concentration(50×10^-4)for 20 min, as measured group, 8 additional intact and 9 IPLs, which were similarly treated but not exposed to Cl₂, served as controls. The changes of lung weigh of IPL(△W)、pressure of pulmonary artery(Pa)and venous pressure(Pv)、airway pressure and tidal volume(TV) were continuously measured and recorded simultaneously. RESULTS: In IPL group: While the perfusing blood flow was kept constant (133.3 mL/min), and Pv did not change, following the exposure, the Pa increased slightly, then the lung weight were increased significantly and the TV decreased . Hematocrit of perfusate of EIPL and parameters of lung water increased also. In intact group: Pa increased slightly, respiratory rate accelerated immediately, and TV decreased. CONCLUSION:Although mean Pa increased continuously and slightly in both intact and IPL group following the exposure to high concentration of Cl₂, the primary cause of edema was most likely to alter pulmonary capillary permeability. The respiratory rate accelerated and TV decreased due to exposure to Cl₂ enhanced hypoxia of intact rabbits.     

NOD proteins and lung diseases

The nucleotide-binding oligomerization domain (NOD) proteins are recently identified as cytosolic pattern recognition receptors located on innate immune and epithelial cells, and recognize pathogen-associated molecular patterns. The NOD1 and NOD2, the two members of NOD protein family, have important roles in innate immunity as sensors of microbial components derived from bacterial peptidoglycan. Besides, NOD proteins have been established as key regulators of cell death and cytokine production, they also have been shown to participate in the pathogeny of allergic disease such as asthma. This review will focus on the identification and functional characterization of NOD proteins, as well as their role in lung diseases.     

Cholecystokinin and lung

Recent studies show that cholecystokinin, a brain-gut peptide, also locates in lung tissues in many animals. Cholecystokinin in lung tissues participates in the modulation of the tone of the tracheae and the pulmonary vessels.It also regulates the breathing pattern as a nerve transmitter in the respiratory center. This paper discusses the location and the biological role of cholecystokinin in lung tissues and focuses on its part during lung diseases.     

Effect of denopamine on alveolar fluid clearance in hypoxic rat lungs

AIM: To study the effect of β1-adrenergic agonist on alveolar fluid clearance in hypoxic rat lungs. METHODS: Rats were exposed to 10% oxygen. Alveolar fluid clearance (AFC) and lung water content (TLW) were calculated in rats exposed to hypoxia for 24 h and 48 h. Isotonic 5% albumin in solutions with different pharmacological agents were instilled into the distal airways in the hypoxia exposed and room air-exposed rat lungs, and the AFC was examined. RESULTS: As compared with the room air-exposed rats (17.50%±2.66%), AFC in the rats exposed to 10% oxygen was not decreased (18.70%±3.19%), AFC in the rats exposed to 10% oxygen for 48 h was decreased (8.59%±2.60%). Denopamine, a β1-adrenergic agonist, increased AFC significantly in the rats exposed to room air and hypoxia. The potency of 10-5 mol/L denopamine was similar to that of 10-5mol/L terbutaline. The denopamine effect was partly blocked by inhibitors of sodium transport amiloride and ouabain (AFC were 11.80%±2.79% and 8.53%±2.17%). CONCLUSION: Denopamine, a selective β1-adrenergic agonist, stimulates alveolar fluid clearance in rats exposed to hypoxia through the active sodium transport, and may have therapeutical effect on pulmonary edema after acute lung injury.     

Progress in relationship between epithelial sodium channel and related respiratory diseases

Epithelial sodium channel (ENaC) is an ion channel widely distributed in various tissues and organs of human. It is composed of 3 homologous subunits and allows the flow of sodium ion across epithelial cells, maintain?ing water-salt balance in the cells. Recent studies show that abnormal expression or dysfunction of ENaC in the respiratory system affects water-salt balance, fluid transportation and cell mobility, and causes abnormal changes of the airway surface liquid level and impaired clearance. ENaC is closely related to the development of respiratory diseases, such as cystic fibrosis, asthma and chronic obstructive pulmonary disease. This article reviews the progress in ENaC structure, function and roles in related respiratory diseases in order to provide a reference for the treatment of the diseases.     

Diagnostic and prognostic value of serum AQP4 antibody on neuromyelitis optica

AIM: To investigate the diagnostic and prognostic value of the serum AQP4 antibody on neuromyelitis optica (NMO). METHODS: Sera of the patients with NMO,transverse myelitis （TM）, optic neuritis (ON), multiple sclerosis (MS) and other neurological disease (OND) were all collected and detected for the presence of AQP4 antibody by CBA. The positive rates and the titers of AQP4 antibody were compared among all the groups. The characteristics of NMO patients with AQP4 antibody positive and those AQP4 antibody negative were also compared. The sensitivity and specificity of serum AQP4 antibody for diagnosis of NMO were evaluated with receiver operating characteristic(ROC) curve. The Kaplan-Meier curve was used to examine the accumulated rate of AQP4 antibody for the progress to NMO.RESULTS: The AQP4 antibody positive rate in NMO group was the highest (87.50%). Orderly, rLETM group was 85.71%，RION group was 80.00%, LETM group was 30.70%, BON group was 8.00%, and MS group was 3.85%. The AQP4 antibody was negative in OND group. There was significant difference between AQP4 antibody positive and AQP4 antibody negative NMO patients on gender, the number of patients with poor visual outcome, time of NMO diagnose confirmed(P<0.05). The sensitivity and specificity were 87.5% and 85.4% for discriminating NMO from other diseases. The Kaplan-Meier curve showed that AQP4-Ab-positive patients were more likely to become NMO compared to the AQP4-Ab-negative patients.CONCLUSION: The serum AQP4 antibody is extensively important in the early diagnosis and prognosis of the NMO with high sensitivity and high specificity.     

Effect of panaxadiols on AQP1 expression in lungs of LPS shock rats

AIM：To investigate the alteration of aquaporin 1 (AQP1) expression in lung tissues in endotoxic shock rats and the effect of panaxadiols.METHODS：The histological changes were examined by HE staining.The expression of AQP1 was analyzed by immunohistochemical staining and Western blotting.RESULTS：(1) Significant inflammatory changes in pulmonary interstitial in rats of LPS group were observed.However,in dexamethasone (DEX) treatment group and panaxadiols (PDS) treatment group,the pulmonary pathologic changes were much slighter.(2) Positive AQP expression in the endothelium of capillary vessels on the wall of alveolus were seen in control (CTR) group,while merely very weak expression in LPS group was detected.The positive staining in PDS groups and DEX group were significantly stronger than that in LPS group,and close to CTR group.(3) The results of Western blotting showed that the quantity of AQP1 expression in LPS group was significantly lower than that in other groups,also the expression in PDS groups and DEX group was slightly lower than that in control group.CONCLUSION：LPS inhibits the expression of AQP1,while PDS increases the strength of AQP1 expression in lungs of endotoxic shock rats.