Microsomal membrane fluidity and phosphatidylcholine synthesis in rabbit lung under high oxygen tension

Abstract

Phosphatidylcholine metabolism and membrane fluidity were studied in microsomes isolated from rabbit lung, which had been exposed to high oxygen tension for 30 min. In these microsomes the incorporation of [3H]-palmitate into phosphatidylcholine increased whereas the incorporation of [14C]-glycerol and [14C]-choline from CDP-[methyl-14C]-choline remained unchanged in comparison to the control microsomes. The enhanced [3H]-palmitate incorporation may be explained by an increase of the specific activity of acyl-CoA:lysophosphatidylcholine acyltransferase which was measured in microsomes from hyperoxic lung. Although microsomal parameters influencing membrane fluidity, such as the cholesterol/phospholipid molar ratio, unsaturation degree of phospholipid acyl chains and lipid/protein ratio, are altered after oxygen treatment in vivo, no change of fluorescence polarization (PDPH) and lipid structural order parameter (SDPH) could be measured. Probably, the membrane maintains its fluidity by counteracting effects on different factors on which the fluidity depends.

Composition, biophysical properties, and morphometry of plasma membranes in pulmonary interstitial edema

“…These data are in accordance with those obtained in cultured cells and tissues (1,5,16,29). The increase of membrane fluidity can also be explained by a change in fatty acid lipid composition that causes an increase in free volume between the lipid chains, due to the presence of double bounds in fatty acids (18:2 and 20:4), leading to a bend in the lipid chain itself.…”

Protective Effects of Polyenoylphosphatidylcholine in Rats With Severe Acute Pancreatitis

“…Previous studies have shown that the PPC could increase liver cell membrane fluidity, microsomal membrane fluidity of the lung, and cell membrane fluidity of erythrocytes. 9,15,37 The results of this study suggest that PPC could not only improve pancreatic acinar cell membrane fluidity and calcium pump activity but could also moderate pancreatic tissue damage caused by decreased OFRs. Further studies are necessary to define the role of PPC, which has shown a broad spectrum of activity.…”

“…In addition to the content of cholesterol and proteins as well as the nature and charge of the polar head groups of the phospholipids, membrane fluidity depends on the length of the fatty acid chains of the phospholipids as well as the number and type of their double bonds. 15,16 In the present study, we would like to investigate whether PPC can alter the course of SAP in rats.…”

“…[9][10][11][12][13] Some previous studies show that PPC has bioprotective effects on nonhepatic tissues and cells. 10,11,14,15 Phospholipids are essential components of all cellular and subcellular membranes, with phosphatidylcholine and phosphatidylethanolamine being the most abundant, and have the ability to form lipid bilayers. Biological membranes are complex mixtures of lipids and proteins.…”

An Early Marker of Hyperoxic Lung Injury in the Rat and Its Pharmacological Modulation

“…In the first, lung homogenates from rats exposed to 100 % oxygen for 24 h showed reduced uptake of oxygen (in the presence of succinate and ADP) compared with homogenates from control animals [9]. In the second, when rabbits underwent ventilation with an increased Fi O2 for 30 min, the lung microsomal phospholipid fatty acid composition was found to be significantly altered [10]. In the third, acid precipitable hydroxyproline was reported to be significantly increased in endobronchial washings from rats after 24 h exposure to 100% oxygen [11].…”