Lung fluid absorption is induced in preterm guinea pigs ventilated with low tidal volumes.

Lung fluid absorption is induced in preterm guinea pigs ventilated with low tidal volumes.

Koshy Shyny; Beard LaMonta L; Kuzenko Stephanie R; Li Tianbo; Folkesson Hans G

Experimental lung research

2011

2011-02

The objective of this study was to determine if low tidal volume (V(t)) ventilation was beneficial when ventilating preterm fetuses. The authors ventilated preterm guinea pig fetuses at gestation day (GD) 67, 3 days before birth, newborn, and 10-day-old (PD10) guinea pigs with low V(t) (6 mL/kg body weight [bw]) and compared them to age-matched fetuses/animals ventilated with higher potentially injurious V(t) (12 mL/kg bw). Lung fluid absorption was measured after intratracheal instillation of 5% albumin in 0.9% NaCl. Low V(t) ventilation stimulated lung fluid absorption when compared to higher V(t) in all groups. The increased lung fluid absorption in low V(t)-ventilated fetuses was associated with increased alpha epithelial Na channel (alphaEnaC) mRNA. However, alphaENaC and betaENaC protein was unchanged over the 1-hour study. Because stretch induces mitogen-activated protein (MAP) kinase expression and MAP kinases may affect lung fluid absorption, the authors investigated if MAP kinase (MAPK) expression was affected by V(t). Extracellular signal-regulated kinase (ERK) and MAPK/ERK kinase (MEK) were phosphorylated in the higher V(t)-ventilated guinea pig fetuses. This suggested that a reduced activation of MAP kinases might explain the increased lung fluid absorption in the low V(t)-ventilated fetuses. Thus these data suggest that low V(t) ventilation increases fetal lung fluid absorption and thus may be preferential to use clinically.

Time Factors; Animals; Gestational Age; Guinea Pigs; *Premature Birth; Phosphorylation; Enzyme Activation; Permeability; Extracellular Signal-Regulated MAP Kinases/metabolism; Intubation; Epithelial Sodium Channels/metabolism; Absorption; Sodium-Potassium-Exchanging ATPase/metabolism; Fetal Organ Maturity; Epinephrine/blood; Extravascular Lung Water/*metabolism; *Tidal Volume; Albumins/administration & dosage/*metabolism; Hydrocortisone/blood; Lung/embryology/*metabolism/physiopathology; MAP Kinase Kinase Kinases/metabolism; Ventilator-Induced Lung Injury/metabolism/physiopathology/*prevention & control; Newborn; Intratracheal; Artificial/adverse effects/*methods; Respiration

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