title: Influence of bilirubin on surface tension properties of lung surfactant.
abstract: OBJECTIVE
  To investigate the influence of bilirubin on the surface tension activity of a porcine derived (Curosurf) and synthetic (Exosurf) surfactant.
  
  
  METHODS
  The captive bubble surfactometer at phospholipid doses of 0.5 mg/ml (low dose) and 1 mg/ml (high dose) in solutions of increasing bilirubin concentrations (0.25, 0.5, and 1.0 mg/ml) was used.
  
  
  RESULTS
  Curosurf (without bilirubin) showed a higher surface f1p4ion activity than Exosurf, as shown by area compression of 30 (SD 0.6)% compared with 76(1.4)% at low surfactant dose and 25 (0.9)% compared with 85 (0.5)% at high dose (P < 0.01). Bilirubin showed negligible surface activity at the concentrations studied. At low phospholipid dose (0.5 mg/ml Curosurf), bilirubin increased film area compression of lipid extract surfactant from 30 (0.6)% to 55 (1.6)%, 59 (0.1)%, and 68 (0.5)% at the three studied bilirubin concentrations, respectively (P < 0.01). At high phospholipid dose (1 mg/ml Curosurf), bilirubin had the same adverse, although less pronounced, effect on film area compression of porcine lipid extract surfactant (25 (0.9)% vs 26 (0.9)%, 39 (1.3)%, and 44 (1.1)%, respectively) (P < 0.01). Using synthetic surfactant (Exosurf), with a much lower original surface activity, bilirubin did not further inhibit its surface tension properties at any of the phospholipid doses studied.
  
  
  CONCLUSIONS
  These results indicate that in vitro bilirubin impairs the surface tension activity of porcine lipid extract surfactant, but does not affect synthetic surfactant activity.
authors.affiliation: Institute of Anatomy, University of Berne, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Amato
authors.forename: S
authors.initials: S
authors.lastname: Schürch
authors.forename: R
authors.initials: R
authors.lastname: Grunder
authors.forename: H
authors.initials: H
authors.lastname: Bachofen
authors.forename: P H
authors.initials: PH
authors.lastname: Burri
mesh_terms: D001663:Bilirubin / Q000494:pharmacology*; D001688:Biological Products; D004338:Drug Combinations; D005233:Fatty Alcohols / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D010743:Phospholipids / Q000494:pharmacology; D010767:Phosphorylcholine; D011092:Polyethylene Glycols / Q000737:chemistry; D011663:Pulmonary Surfactants / Q000737:chemistry*; D013500:Surface Tension
chemical_list: D001688:Biological Products; D004338:Drug Combinations; D005233:Fatty Alcohols; D010743:Phospholipids; D011663:Pulmonary Surfactants; D010767:Phosphorylcholine; D011092:Polyethylene Glycols; C047049:dipalmitoylphosphatidylcholine, hexadecanol, tyloxapol drug combination; C068291:poractant alfa; D001663:Bilirubin