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Effects of albumin and erythrocyte membranes on spread monolayers of lung surfactant lipids

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Title Effects of albumin and erythrocyte membranes on spread monolayers of lung surfactant lipids
 
Creator RACHANA, R
BANERJEE, R
 
Subject biological membranes
cholesterol
monolayers
phospholipid
 
Description Dipalmitoyl phosphatidylcholine (DPPC), one of the main constituents of lung surfactant is mainly responsible for reduction of surface tension to near 0 mN/m during expiration, resisting alveolar collapse. Other unsaturated phospholipids like palmitoyloleoyl phosphatidylglycerol (PG), palmitoyloleoyl phosphatidylcholine (POPC) and neutral lipids help in adsorption of lung surfactant to the air-aqueous interface. Lung surfactant lipids may interact with plasma proteins and hematological agents flooding the alveoli in diseased states. In this study, we evaluated the effects of albumin and erythrocyte membranes on spread films of DPPC alone and mixtures of DPPC with each of PG, POPC, palmitoyloleoyl phosphatidylethanolamine (PE), cholesterol (CHOL) and palmitic acid (PA) in 9:1 molar ratios. Surface tension-area isotherms were recorded using a Langmuir-Blodgett (LB) trough at 37 °C with 0.9% saline as the sub-phase. In the presence of erythrocyte membranes, DPPC and DPPC + PA monolayers reached minimum surface tensions of 7.3 ± 0.9 and 9.6 ± 1.4 mN/m, respectively. Other lipid combinations reached significantly higher minimum surface tensions >18 mN/m in presence of membranes (Newman Keul's test, p < 0.05). The relative susceptibility to membrane inhibition was [(DPPC + PG, 7:3) = (DPPC + PG, 9:1) = (DPPC + POPC) = (DPPC + PE) = (DPPC + CHOL)] > [(DPPC + PA) = (DPPC)]. The differential response was more pronounced in case of albumin with DPPC and DPPC + PA monolayers reaching minimum surface tensions less than 2.4 mN/m in presence of albumin, whereas DPPC + PG and DPPC + POPC reached minimum surface tensions of around 20 mN/m in presence of albumin. Descending order of susceptibility of the spread monolayers of lipid mixtures to albumin destabilization was as follows: [(DPPC + PG, 7:3) = (DPPC + PG, 9:1) = (DPPC + POPC)] > [(DPPC + PE) = (DPPC + CHOL)] > [(DPPC + PA) = (DPPC)] The increase in minimum surface tension in presence of albumin and erythrocyte membranes was accompanied by sudden increases in compressibility at surface tensions of 15-30 mN/m. This suggests a monolayer destabilization and could be indicative of phase transitions in the mixed lipid films due to the presence of the hydrophobic constituents of erythrocyte membranes.
 
Publisher Elsevier
 
Date 2009-05-14T13:34:57Z
2011-12-08T07:17:05Z
2011-12-26T13:02:04Z
2011-12-27T05:48:00Z
2009-05-14T13:34:57Z
2011-12-08T07:17:05Z
2011-12-26T13:02:04Z
2011-12-27T05:48:00Z
2006
 
Type Article
 
Identifier Colloids and Surfaces B: Biointerfaces 50(1), 9-17
09277765
10.1016/j.colsurfb.2006.03.017
http://hdl.handle.net/10054/1360
http://dspace.library.iitb.ac.in/xmlui/handle/10054/1360
 
Language en