Properties of modified natural surfactant after exposure to fibrinogen in vitro and in an animal model of respiratory distress syndrome.
BACKGROUND
Plasma proteins are known to interfere with pulmonary surfactant. Studies have proven the hypothesis that fibrinogen preserves exogenous surfactant subjected to long-term surface area cycling.


METHODS
The exogenous surfactant Curosurf was subjected to long-term surface area cycling without or with fibrinogen (ratio 2:1 w/w) and was tested by captive bubble surfactometer and on newborn premature rabbits.


RESULTS
Surface tension increased in Curosurf (80 mg/ml) samples without fibrinogen after 6-12 d of cycling. In samples with fibrinogen the cycling time had no effect on surface tension. Addition of fibrinogen to surfactant prevented lipid peroxidation. Lung gas volumes of animals with noncycled Curosurf or Curosurf cycled with fibrinogen for 6 d were comparable and higher than in rabbits with Curosurf cycled without fibrinogen. Alveolar volume density was higher in groups with noncycled Curosurf or Curosurf cycled with fibrinogen than in Curosurf cycled without fibrinogen (both P < 0.001).


CONCLUSIONS
The effect of fibrinogen on pulmonary surfactant cycled at 37 °C depends both on surfactant concentration and cycling time. At high phospholipid concentration used in clinical practice fibrinogen has a protective effect on biophysical and physiological properties of natural modified surfactant subjected to surface area cycling. This effect is partially mediated by reduction in lipid peroxidation.
Laboratory for Surfactant Research, Department of Molecular Medicine and Surgery, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden. calkovska@jfmed.uniba.sk
Andrea
A
Calkovska
Bim
B
Linderholm
Marie
M
Haegerstrand-Björkman
Tore
T
Curstedt
D000818:Animals; D004195:Disease Models, Animal; D005340:Fibrinogen / Q000737:chemistry*; D006801:Humans; D007231:Infant, Newborn; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000378:metabolism*; D011817:Rabbits; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology*; D013500:Surface Tension
D011663:Pulmonary Surfactants; D005340:Fibrinogen