title: Increased expression of AQP 1 and AQP 5 in rat lungs ventilated with low tidal volume is time dependent.
abstract: OBJECTIVE
  Mechanical ventilation (MV) can induce or worsen pulmonary oedema. Aquaporins (AQPs) facilitate the selective and rapid bi-directional movement of water. Their role in the development and resolution of pulmonary oedema is controversial. Our objectives are to determine if prolonged MV causes lung oedema and changes in the expression of AQP 1 and AQP 5 in rats.
  
  
  METHODS
  25 male Wistar rats were subjected to MV with a tidal volume of 10 ml/kg, during 2 hours (n = 12) and 4 hours (n = 13). Degree of oedema was compared with a group of non-ventilated rats (n = 5). The expression of AQP 1 and AQP 5 were determined by western immunoblotting, measuring the amount of mRNA (previously amplified by RT-PCR) and immunohistochemical staining of AQPs 1 and 5 in lung samples from all groups.
  
  
  RESULTS
  Lung oedema and alveolar-capillary membrane permeability did not change during MV. AQP-5 steady state levels in the western blot were increased (p<0.01) at 2 h and 4 h of MV. But in AQP-1 expression these differences were not found. However, the amount of mRNA for AQP-1 was increased at 2 h and 4 h of MV; and for AQP 5 at 4 h of MV. These findings were corroborated by representative immunohistochemical lung samples.
  
  
  CONCLUSIONS
  In lungs from rats ventilated with a low tidal volume the expression of AQP 5 increases gradually with MV duration, but does not cause pulmonary oedema or changes in lung permeability. AQPs may have a protective effect against the oedema induced by MV.
authors.affiliation: Hospital General Universitario, Valencia, Spain.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Fabregat
authors.affiliation: Hospital Clínico Universitario, Valencia, Spain; Instituto de Investigación Clínica (INCLIVA), Fundación de Investigación Hospital Clínico Universitario, Valencia, Spain.
authors.forename: José
authors.initials: J
authors.lastname: García-de-la-Asunción
authors.affiliation: Department of Pharmacology, School of Medicine, University of Valencia, Valencia, Spain.
authors.forename: Benjamín
authors.initials: B
authors.lastname: Sarriá
authors.affiliation: Department of Pharmacology, School of Medicine, University of Valencia, Valencia, Spain; Research Foundation of Hospital General Universitario, Valencia, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Cortijo
authors.affiliation: School of Medicine, University of Valencia, Valencia, Spain, andAnaesthesia and Critical Care Department, Hospital General Universitario, Valencia, Spain.
authors.forename: José
authors.initials: J
authors.lastname: De Andrés
authors.affiliation: Department of Physiology, School of Medicine, University of Valencia, Valencia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Mata
authors.affiliation: Hospital Clínico Universitario, Valencia, Spain; Instituto de Investigación Clínica (INCLIVA), Fundación de Investigación Hospital Clínico Universitario, Valencia, Spain.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Pastor
authors.affiliation: School of Medicine, University of Valencia, Valencia, Spain, and Anaesthesia and Critical Care Department, Hospital Clínico Universitario, Valencia, Spain; Instituto de Investigación Clínica (INCLIVA), Fundación de Investigación Hospital Clínico Universitario, Valencia, Spain.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Belda
mesh_terms: D000818:Animals; D051398:Aquaporin 1 / Q000235:genetics / Q000378:metabolism*; D051402:Aquaporin 5 / Q000235:genetics / Q000378:metabolism*; D002199:Capillary Permeability; D005786:Gene Expression Regulation; D006439:Hemodynamics; D008168:Lung / Q000378:metabolism / Q000502:physiology* / Q000503:physiopathology; D008297:Male; D010100:Oxygen / Q000378:metabolism; D011654:Pulmonary Edema / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D012121:Respiration, Artificial / Q000009:adverse effects; D013990:Tidal Volume
chemical_list: D051402:Aquaporin 5; D051398:Aquaporin 1; D010100:Oxygen