Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0034063 (pulmonary edema)
 10,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mammalian peripheral lung contains at least three aquaporin (AQP) water channels: AQP1 in microvascular endothelia, AQP4 in airway epithelia, and AQP5 in alveolar epithelia. In this study, we determined the role of AQP4 in airspace-to-capillary water transport by comparing water permeability in wild-type mice and transgenic null mice lacking AQP1, AQP4, or AQP1/AQP4 together. An apparatus was constructed to measure lung weight continuously during pulmonary artery perfusion of isolated mouse lungs. Osmotically induced water flux (J(v)) between the airspace and capillary compartments was measured from the kinetics of lung weight change in saline-filled lungs in response to changes in perfusate osmolality. J(v) in wild-type mice varied linearly with osmotic gradient size (4.4 x 10(-5) cm(3) s(-1) mOsm(-1)) and was symmetric, independent of perfusate osmolyte size, weakly temperature dependent, and decreased 11-fold by AQP1 deletion. Transcapillary osmotic water permeability was greatly reduced by AQP1 deletion, as measured by the same method except that the airspace saline was replaced by an inert perfluorocarbon. Hydrostatically induced lung edema was characterized by lung weight changes in response to changes in pulmonary arterial inflow or pulmonary venous outflow pressure. At 5 cm H(2)O outflow pressure, the filtration coefficient was 4.7 cm(3) s(-1) mOsm(-1) and reduced 1.4-fold by AQP1 deletion. To study the role of AQP4 in lung water transport, AQP1/AQP4 double knockout mice were generated by crossbreeding of AQP1 and AQP4 null mice. J(v) were (cm(3) s(-1) mOsm(-1) x 10(-5), SEM, n = 7-12 mice): 3.8 +/- 0. 4 (wild type), 0.35 +/- 0.02 (AQP1 null), 3.7 +/- 0.4 (AQP4 null), and 0.25 +/- 0.01 (AQP1/AQP4 null). The significant reduction in P(f) in AQP1 vs. AQP1/AQP4 null mice was confirmed by an independent pleural surface fluorescence method showing a 1.6 +/- 0.2-fold (SEM, five mice) reduced P(f) in the AQP1/AQP4 double knockout mice vs. AQP1 null mice. These results establish a simple gravimetric method to quantify osmosis and filtration in intact mouse lung and provide direct evidence for a contribution of the distal airways to airspace-to-capillary water transport.
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PMID:Role of aquaporin-4 in airspace-to-capillary water permeability in intact mouse lung measured by a novel gravimetric method. 1061 15

The mammalian lung expresses water channel aquaporin-1 (AQP1) in microvascular endothelia, AQP4 in airway epithelia, and AQP5 at the apical plasma membrane in type I cells of alveolar epithelia. We previously studied the role of AQP1 and AQP4 in lung fluid transport using knockout mice. Here, we examined the role of AQP5 using AQP5 knockout mice, which were recently shown to manifest defective saliva secretion. AQP5 deletion did not affect lung morphology at the light microscopic level, nor did it affect the distribution or expression of aquaporins 1, 3, or 4. Airspace-capillary osmotic water permeability (P(f)) was measured in isolated perfused lungs by pleural surface fluorescence and gravimetric methods. P(f) was reduced 10-fold by AQP5 deletion and was further reduced by 2- to 3-fold in AQP1/AQP5 double-knockout mice. Hydrostatic lung edema in response to acute increases in pulmonary artery pressure was not affected by AQP5 deletion. Active alveolar fluid absorption was measured in an in situ lung model from the increase in concentration of a volume marker in an isosmolar alveolar instillate. Interestingly, fluid absorption did not differ in litter-matched AQP5 knockout mice, nor was there an effect of AQP5 deletion when fluid absorption was maximally stimulated by pretreatment of mice with keratinocyte growth factor. These results indicate that AQP5 is responsible for the majority of water transport across the apical membrane of type I alveolar epithelial cells. The unimpaired alveolar fluid clearance in AQP5-null mice indicates that high alveolar water permeability is not required for active, near-isosmolar fluid transport.
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PMID:Lung fluid transport in aquaporin-5 knockout mice. 1061 56

Aquaporins (AQPs) are water channel proteins that permit osmotically driven water movement. To determine their dynamics in pulmonary oedema, we examined the expression of mRNA and protein for AQP1, AQP3, AQP4, and AQP5 in the lungs of normal and thiourea-treated rats. In the thiourea group, lung water content increased significantly (vs. controls) with the peak at around 4 h. Semi-quantitative RT-PCR showed that AQP3 mRNA in the thiourea group rose significantly, peaking at around 4-8 h. The expression of AQP1, AQP4, AQP5, ENaC and CFTR mRNA each decreased significantly some time after the peak in lung water content. Immunoblot analysis showed that glycosylated AQP3 protein was increased 4-10 h after treatment. Expression of the other AQP proteins was not significantly altered, except for that of AQP4. Immunohistochemical examination revealed that AQP1 was expressed in endothelia, AQP3 in the basal cells of the large airways and in cuboidal cells in the bronchioles, AQP4 in the basolateral membrane of airway cells and AQP5 in type-I pneumocytes. Our results suggest that AQP3 is expressed not only in large airways, but also in bronchioles, and is related to water movement in pulmonary oedema.
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PMID:Bronchiolar expression of aquaporin-3 (AQP3) in rat lung and its dynamics in pulmonary oedema. 1524 66

Ovalbumin (OVA)-induced asthma in mouse lungs causes changes in the mRNA and protein levels of aquaporins (AQPs). AQP expression was examined in the presence of various anti-asthmatic agents, including dexamethasone, ambroxol, and terbutaline. The influence of these agents on OVA-induced airway inflammation was also evaluated. The mRNA expression levels of AQP1, 4, and 5 were significantly reduced and that of AQP3 was significantly increased 24h after the last OVA exposure. The protein levels of AQP1, 3, and 5 mirrored the mRNA expression profiles, but AQP4 did not exhibit any changes. Only the mRNA and protein expression levels of AQP1 and AQP5 were significantly increased by these three anti-asthmatic agents. Dexamethasone and ambroxol improved the eosinophil infiltration, mucus secretion, and pulmonary edema caused by OVA, but terbutaline only alleviated pulmonary edema. These results indicate that AQP1 and AQP5 are closely related to pulmonary edema but not to eosinophil infiltration or mucus secretion during asthma. Anti-asthmatic agents could alleviate pulmonary edema through upregulating the expression of AQP1 and AQP5 in mouse lungs that have OVA-induced asthma.
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PMID:Anti-asthmatic agents alleviate pulmonary edema by upregulating AQP1 and AQP5 expression in the lungs of mice with OVA-induced asthma. 2222 56

Acute lung injury (ALI) occurs frequently in patients with severe traumatic brain injury (TBI) and is associated with a poor clinical outcome. Aquaporins (AQPs), particularly AQP1 and AQP4, maintain water balances between the epithelial and microvascular domains of the lung. Since pulmonary edema (PE) usually occurs in the TBI-induced ALI patients, we investigated the effects of a thaliporphine derivative, TM-1, on the expression of AQPs and histological outcomes in the lung following TBI in rats. TM-1 administered (10 mg/kg, intraperitoneal injection) at 3 or 4 h after TBI significantly reduced the elevated mRNA expression and protein levels of AQP1 and AQP4 and diminished the wet/dry weight ratio, which reflects PE, in the lung at 8 and 24 h after TBI. Postinjury TM-1 administration also improved histopathological changes at 8 and 24 h after TBI. PE was accompanied with tissue pathological changes because a positive correlation between the lung injury score and the wet/dry weight ratio in the same animal was observed. Postinjury administration of TM-1 improved ALI and reduced PE at 8 and 24 h following TBI. The pulmonary-protective effect of TM-1 may be attributed to, at least in part, downregulation of AQP1 and AQP4 expression after TBI.
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PMID:Thaliporphine derivative improves acute lung injury after traumatic brain injury. 2570 83

Dexamethasone can alleviate the severity of bronchial and alveolar edema and therefore is widely applied in the treatment of various exudative diseases including pulmonary edema. However, the effectiveness of dexamethasone is still being questioned and its mechanism is not fully understood. Aquaporins (AQPs) are mainly responsible for the transmembrane transport of water, which is tightly associated with pulmonary edema. Small ubiquitin-like modifiers (SUMOs) are considered to play a protective role in some pathological conditions. In this study, we demonstrated that dexamethasone can upregulate the expression of AQPs in A549 cells by inducing SUMOylation. We found that a low dose of dexamethasone significantly upregulated the levels of SUMOylation and AQP expression in A549 cells, accompanied by a translocation of SUMOs from the cytoplasm to the nucleus. We also explored the possible relation between SUMOylation and AQPs. Knockdown of SUMO2/3 by RNA interference decreased the level of AQP4 in A549 cells after dexamethasone stimulation. Together, our findings demonstrated that AQP4 expression was upregulated in A549 cells exposed to dexamethasone, and SUMOylation may participate in the regulation of AQP4.
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PMID:Dexamethasone Upregulates the Expression of Aquaporin4 by Increasing SUMOylation in A549 Cells. 3249 29