Biophysical activity of synthetic phospholipids combined with purified lung surfactant 6000 Dalton apoprotein

✍ Scribed by R.H. Notter; D.L. Shapiro; B. Ohning; J.A. Whitsett

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 987 KB
• Volume: 44
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(87)90002-8

✦ Synopsis

This research studies the biophysical surface activity of synthetic phospholipids combined in vitro with purified lung surfactant apoprotein, having an M r of 6000. Hydrophobic surfactant.associated protein (SAP-6) was delipidated and purified from both bovine and canine lung lavage, and was combined in vitro with a syn¼hetic phospholipid mLxture (SM) of similar composition to natural lung surfactant phospholipids. SM phospholipids were also combined and studied biophydcally with another purified surfactant-associated protein, SAP-35. The biophysical activity of synthetic phospholipid-apoprotein combinants was assessed by measurements of adsorption facility and dynamic surface tendon lowering ability at 37°C. The SM-SAP-6 combinants had adsorption facility equivalent to natural lung surfactant, and to the surfactant extract preparations CLSE and surfactant-TA used in exogenous surfactant replacement therapy for the neonatal Respiratory Distress Syndrome (RDS). The synthetic phospholipid-SAP-6 combinants also lowered surface tension to < 1 dyne/cm under dynamic compression in an oscillating bubble apparatus at concentrations as low as 0.5 mg phospholipid/ml. A stn3cin 8 finding was that this excellent dynamic surface activity was preserved as SAP-6 composition was reduced to values as low as 5 ttg/5 mg SM phospholipid (0. I% SAP-6 protein), an order of masnitude less than the 1% protein content of CLSE and suffactant-TA. Mixtures of SM phospholipids plus SAP-35, the major surfactant glycoprotein, had sisnificantly lower biophysical activity, which did not approach that of a functional lung i surfactant. These results suggest that synthetic exogenous surfactants of potential utility for replacement therapy in RDS can be formulated by combining synthetic phospholipids in vitro with specifically purified, hydrophobic surfactant-assoclated protein, SAP-6.