Reduced surface tension normalizes static lung mechanics in a rodent chronic heart failure model.
BACKGROUND
Chronic elevation of pulmonary microvascular pressure in chronic heart failure results in compensatory changes in the lung that reduce alveolar fluid filtration and protect against pulmonary microvascular rupture.


OBJECTIVE
To determine whether these compensatory responses may have maladaptive effects on lung function.


METHODS
Six weeks after myocardial infarction (chronic heart failure model) rat lung composition, both gross and histologic; air and saline mechanics; surfactant production; and immunological mediators were examined.


RESULTS
An increase in dry lung weight, due to increased insoluble protein, lipid and cellular infiltrate, without pulmonary edema was found. Despite this, both forced impedance and air pressure-volume mechanics were normal. However, there was increased tissue stiffness in the absence of surface tension (saline pressure-volume curve) with a concurrent increase in both surfactant content and alveolar type II cell numbers, suggesting a novel homeostatic phenomenon.


CONCLUSIONS
These studies suggest a compensatory reduction in pulmonary surface tension that attenuates the effect of lung parenchymal remodeling on lung mechanics, hence work of breathing.
Intensive and Critical Care Unit, Flinders Medical Centre, Bedford Park, Adelaide, South Australia 5042, Australia. dani.dixon@flinders.edu.au
Dani-Louise
DL
Dixon
Carmine G
CG
De Pasquale
Hilde R
HR
De Smet
Sonja
S
Klebe
Sandra
S
Orgeig
Andrew D
AD
Bersten
D000403:Airway Resistance / Q000502:physiology; D000818:Animals; D002908:Chronic Disease; D004195:Disease Models, Animal; D006333:Heart Failure / Q000150:complications / Q000473:pathology* / Q000503:physiopathology*; D008168:Lung / Q000473:pathology* / Q000503:physiopathology*; D008297:Male; D008833:Microcirculation / Q000502:physiology; D009929:Organ Size; D011652:Pulmonary Circulation / Q000502:physiology; D037661:Pulmonary Surfactant-Associated Proteins / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015656:Respiratory Mechanics / Q000502:physiology*; D013500:Surface Tension; D014655:Vascular Resistance / Q000502:physiology*
D037661:Pulmonary Surfactant-Associated Proteins