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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Subczynski, W. K. Hyde, J. S. Kusumi, A. |
| Description | Author Affiliation: Subczynski WK ( Department of Radiology, Medical College of Wisconsin, Milwaukee 53226.); |
| Abstract | Oxygen transport in phosphatidylcholine-cholesterol membranes has been studied by observing the collision of molecular oxygen with nitroxide radical spin labels placed at various distances from the membrane surface using long-pulse saturation recovery ESR techniques. The collision rate was estimated for tempocholine phosphatidic acid ester, 5-doxylstearic acid, and 16-doxylstearic acid from spin-lattice relaxation times (T1) measured in the presence and absence of molecular oxygen. Profiles of the local oxygen transport parameter across the membrane were obtained as a function of cholesterol mol fraction and temperature in L-alpha-dimyristoylphosphatidylcholine ([ Myr2]PtdCho) and L-alpha-dioleoylphosphatidylcholine ([ Ole2]PtdCho) membranes. Membrane oxygen permeability coefficients were estimated from oxygen transport parameter profiles. At approximately 30 degrees C, the oxygen permeability coefficients in the presence and absence of 50 mol % cholesterol are 22.7 and 125.2 cm/s, respectively, for [Myr2]PtdCho membranes, and 54.7 and 114.2 cm/s, respectively, for [Ole2]PtdCho membranes (compared with 60-80 cm/s for water layers with the same thicknesses as the membranes). The major results in the liquid-crystalline phase are as follows: (i) In the absence of cholesterol, membranes are not barriers to oxygen transport. (ii) Addition of 50 mol % cholesterol decreases oxygen permeability by a factor of approximately 5 and approximately 2.5 in [Myr2]PtdCho and [Ole2]PtdCho membranes, respectively. The resistance to oxygen transport is located in and near the polar headgroup regions in the membrane. (iii) Cholesterol increases oxygen transport in the central regions of [Ole2]PtdCho membranes. |
| ISSN | 00278424 |
| e-ISSN | 10916490 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Issue Number | 12 |
| Volume Number | 86 |
| Language | English |
| Publisher | National Academy of Sciences |
| Publisher Date | 1989-07-01 |
| Publisher Place | United States |
| Access Restriction | Open |
| Subject Keyword | Cholesterol Dimyristoylphosphatidylcholine Liposomes Oxygen Phosphatidylcholines Electron Spin Resonance Spectroscopy Kinetics Models, Biological Permeability Spin Labels Thermodynamics Research Support, U.S. Gov't, P.H.S. Multidisciplinary |
| Content Type | Text |
| Resource Type | Article |
| Subject | Multidisciplinary |
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