Biophysical characterization and modeling of lung surfactant components

E. P. Ingenito*, L. Mark, J. Morris, F. F. Espinosa, R. D. Kamm, M. Johnson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

The present study characterizes the dynamic interfacial properties of calf lung surfactant (CLS) and samples reconstituted in a stepwise fashion from phospholipid (PL), hydrophobic apoprotein (HA), surfactant apoprotein A (SP-A), and neutral lipid fractions. Dipalmitoylphosphatidylcholine (DPPC), the major PL component of surfactant, was examined for comparison. Surface tension was measured over a range of oscillation frequencies (1-100 cycles/min) and bulk phase concentrations (0.01-1 mg/ml) by using a pulsating bubble surfactometer. Distinct differences in behavior were seen between samples. These differences were interpreted by using a previously validated model of surfactant adsorption kinetics that describes function in terms of 1) adsorption rate coefficient (k1), 2) desorption rate coefficient (k2), 3) minimum equilibrium surface tension (γ*), 4) minimum surface tension at film collapse (γ(min)), and 5) change in surface tension with interfacial area for γ < γ* (m2). Results show that DPPC and PL have k1 and k2 values several orders of magnitude lower than CLS. PL had a γ(min) of 19-20 dyn/cm, significantly greater than CLS (nearly zero). Addition of the HA to PL restored dynamic interfacial behavior to nearly that of CLS. However, m2 remained at a reduced level. Addition of the SP-A to PL + HA restored m2 to a level similar to that of CLS. No further improvement in function occurred with the addition of the neutral lipid. These results support prior studies that show addition of HA to the PL markedly increases adsorption and film stability. However, SP-A is required to completely normalize dynamic behavior.

Original languageEnglish (US)
Pages (from-to)1702-1714
Number of pages13
JournalJournal of applied physiology
Volume86
Issue number5
DOIs
StatePublished - May 1999

Keywords

  • Dynamic
  • Model
  • Surface tension
  • Surfactometer

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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