Mixtures of Low Molecular Weight Surfactant Proteins and Dipalmitoyl Phosphatidylcholine Duplicate Effects of Pulmonary Surfactant in Vitro and in Vivo

Abstract

ABSTRACT. Pulmonary surfactant proteins SP-B and SP-C were isolated from lavage fluids of bovine lungs and recombined (lipid/proteins, 911, wt/wt) with dipalmitoyl phosphatidylcholine for testing in vitro and in surfactantdeficient adult rats. Using a pulsating bubble surfactometer, we found that inflation pressures of bubbles at minimum radii in these mixtures were 0.34 f 0.05 cm H 2 0 (+ SD, n = 24) after 1 min. These values were not affected by increasing amounts of surfactant protein relative to dipalmitoyl phosphatidylcholine (DPPC). Minimum inflation pressures were similar to those of modified bovine surfactant, surfactant Tokyo Akita (TA) (0.33 f 0.05 cm H20, n = 7). I n vivo testing was carried out in adult rats made surfactant deficient by repeated lavage and ventilated with 100% oxygen. Rats received tracheal instillations of either air, DPPC, DPPCISP-B,C (9:1), or surfactant TA at 50 mg/kg body weight. Surfactant TA and DPPCISP-B, SP-C mixtures resulted in similar immediate and sustained improvements in arterial oxygenation (308 + 66 torr, n = 10 and 312 2 101 torr, n = 6 at 30 min posttreatment) that were significantly greater than those of sham (76 f 24 torr, n = 17) and DPPC-treated rats (64 f 32 torr, n = 7). Rats treated with either DPPC/SP-B,C mixtures or surfactant TA showed similar postmortem static lung compliances (2.3 f 0.8 ml/cm H20/kg, n = 8 and 1.9 2 0.4 ml/cm H20/kg, n = 5, respectively) that were significantly larger than sham (1.3 + 0.3 ml/cm H 2 0 / kg, n = 14) and DPPC-treated rats (1.2 f 0.2 ml/cm H20/ kg, n = 6). We conclude that simple mixtures of DPPC

Very low surfactant protein C contents in newborn Belgian White and Blue calves with respiratory distress syndrome

“…The levels of PtdCho and disaturated PtdCho determined here for RDS and healthy BWB calves are close to the 79.2p1.6 % and 52.9p2.5 % (w\w) reported for healthy bovine samples [36]. The total SP-B and SP-C contents in surfactant samples reported in the literature range from 1 % to 2 % (w\w, relative to total phospholipids) [38,39], with a value of 1.2 % for calf lung surfactant extract [40]. The values determined here for healthy BWB calves are in this range and are comparable to the values determined for 37 pig samples with the same procedure as used in this work (SP-B, 0.7p0.1 % ; SP-C, 0.6p0.1 %) [24].…”

Pulmonary Surfactant: Physical Chemistry, Physiology, and Replacement

“…Although both SP-B and SP-C significantly improve the adsorption and overall dynamic surface activity of phospholipids as noted earlier (51,219,220,261,275,303,311,337,339,341), SP-B is significantly more effective in doing so than SP-C (51,219,220,261,311,337). Probably the most pronounced difference in activity between the hydrophobic proteins is that SP-B gives a much greater facilitation in the adsorption of phospholipids compared to SP-C ( Figure 6).…”

“…In the absence of apoproteins, even the complete mix of lung surfactant lipid constituents (phospholipids plus neutral lipids) adsorbs relatively poorly at body temperature. Addition of the hydrophobic apoproteins to lung surfactant phospholipids greatly improves adsorption (Figure 3), and this is also found when either SP-B or SP-C or both are combined with synthetic phospholipids (51,123,214,275,303,311,339,341). SP-A also interacts with phospholipids to increase adsorption (250), and in conjunction with SP-B is responsible for organizing phospholipids into the calcium-dependent tubular myelin microstructure in whole surfactant (325).…”

Lipid bilayer surface association of lung surfactant protein SP-B, amphipathic segment detected by flow immunofluorescence

“…Premature infants with insufficient amounts of lung surfactant suffering from Respiratory Distress Syndrome (RDS) have been successfully treated with exogenous surfactants that contain SP-B and SP-C extracted from animal or human sources (8,(11)(12)(13). Other surfactant therapies mix bovine or porcine SP-B and SP-C with synthetic lipids or extracted lung lipids (6,(14)(15)(16)(17), also with reasonable success. However, the detailed role of SP-B or SP-C in enhancing surfactant function is still not well understood.…”