Surfactant protein interactions with neutral and acidic phospholipid films.
The captive bubble tensiometer was employed to study interactions of phospholipid (PL) mixtures of dipalmitoylphosphatidylcholine (DPPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG) at 50 microg/ml with physiological levels of the surfactant protein (SP) A SP-B, and SP-C alone and in combination at 37 degrees C. All surfactant proteins enhanced lipid adsorption to equilibrium surface tension (gamma), with SP-C being most effective. Kinetics were consistent with the presence of two adsorption phases. Under the conditions employed, SP-A did not affect the rate of film formation in the presence of SP-B or SP-C. Little difference in gamma(min) was observed between the acidic POPG and the neutral POPC systems with SP-B or SP-C with and without SP-A. However, gamma(max) was lower with the acidic POPG system during dynamic, but not during quasi-static, cycling. Considerably lower compression ratios were required to generate low gamma(min) values with SP-B than SP-C. DPPC-POPG-SP-B was superior to the neutral POPC-SP-B system. Although SP-A had little effect on film formation with SP-B, surface activity during compression was enhanced with both PL systems. In the presence of SP-C, lower compression ratios were required with the acidic system, and with this mixture, SP-A addition adversely affected surface activity. The results suggest specific interactions between SP-B and phosphatidylglycerol, and between SP-B and SP-A. These observations are consistent with the presence of a surface-associated surfactant reservoir which is involved in generating low gamma during film compression and lipid respreading during film expansion.
Rodriguez-Capote
K
K
Department of Obstetrics and Gynaecology, University of Western Ontario, London, Ontario N6A 5A5, Canada T2N 4N1.
Nag
K
K
Schürch
S
S
Possmayer
F
F
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000494:pharmacology; D000327:Adsorption; D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology; D002417:Cattle; D004338:Drug Combinations; D004347:Drug Interactions; D006863:Hydrogen-Ion Concentration; D010715:Phosphatidylglycerols / Q000494:pharmacology; D010743:Phospholipids / Q000737:chemistry / Q000494:pharmacology*; D011510:Proteolipids / Q000494:pharmacology; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000494:pharmacology*; D013500:Surface Tension
D001426:Bacterial Proteins; D004338:Drug Combinations; D010715:Phosphatidylglycerols; D010743:Phospholipids; C412006:PopC protein, Ralstonia solanacearum; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D015060:1,2-Dipalmitoylphosphatidylcholine; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol