The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids

Lipids were obtained from high potassium (HK) and low potassium (LK) sheep red cells by sequential extraction of the erythrocytes with isopropanol-chloroform, chloroform-methanol-0.1 M KCl, and chloroform. The extract contained cholesterol and phospholipid in a molar ratio of 0.8:1.0, and less than...

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Main Authors:	Andreoli, Thomas E., Bangham, J. Andrew, Tosteson, Daniel C.
Format:	Online
Language:	English
Published:	The Rockefeller University Press 1967
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2225723/

id	pubmed-2225723
recordtype	oai_dc
spelling	pubmed-22257232008-04-23 The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids Andreoli, Thomas E. Bangham, J. Andrew Tosteson, Daniel C. Article Lipids were obtained from high potassium (HK) and low potassium (LK) sheep red cells by sequential extraction of the erythrocytes with isopropanol-chloroform, chloroform-methanol-0.1 M KCl, and chloroform. The extract contained cholesterol and phospholipid in a molar ratio of 0.8:1.0, and less than 1% protein contaminant. Stable thin lipid membranes separating two aqueous compartments were formed from an erythrocyte lipid-hydrocarbon solution, and had an electrical resistance of ∼108 ohm-cm2 and a capacitance of 0.38–0.4 µf/cm2. From the capacitance values, membrane thickness was estimated to be 46–132 A, depending on the assumed value for the dielectric constant (2.0–4.5). Membrane voltage was recorded in the presence of ionic (NaCl and/or KCl) concentration gradients in the solutions bathing the membrane. The permeability of the membrane to Na+, K+, and Cl- (expressed as the transference number, T ion) was computed from the steady-state membrane voltage and the activity ratio of the ions in the compartments bathing the membrane. T Na and T K were approximately equal (∼0.8) and considerably greater than T Cl (∼0.2). The ionic transference numbers were independent of temperature, the hydrocarbon solvent, the osmolarity of the solutions bathing the membranes, and the cholesterol content of the membranes, over the range 21–38°C. The high degree of membrane cation selectivity was tentatively attributed to the negatively charged phospholipids (phosphatidylethanolamine and phosphatidylserine) present in the lipid extract. The Rockefeller University Press 1967-07-01 /pmc/articles/PMC2225723/ /pubmed/6034765 Text en Copyright © 1967 by The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Andreoli, Thomas E. Bangham, J. Andrew Tosteson, Daniel C.
spellingShingle	Andreoli, Thomas E. Bangham, J. Andrew Tosteson, Daniel C. The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids
author_facet	Andreoli, Thomas E. Bangham, J. Andrew Tosteson, Daniel C.
author_sort	Andreoli, Thomas E.
title	The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids
title_short	The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids
title_full	The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids
title_fullStr	The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids
title_full_unstemmed	The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids
title_sort	formation and properties of thin lipid membranes from hk and lk sheep red cell lipids
description	Lipids were obtained from high potassium (HK) and low potassium (LK) sheep red cells by sequential extraction of the erythrocytes with isopropanol-chloroform, chloroform-methanol-0.1 M KCl, and chloroform. The extract contained cholesterol and phospholipid in a molar ratio of 0.8:1.0, and less than 1% protein contaminant. Stable thin lipid membranes separating two aqueous compartments were formed from an erythrocyte lipid-hydrocarbon solution, and had an electrical resistance of ∼108 ohm-cm2 and a capacitance of 0.38–0.4 µf/cm2. From the capacitance values, membrane thickness was estimated to be 46–132 A, depending on the assumed value for the dielectric constant (2.0–4.5). Membrane voltage was recorded in the presence of ionic (NaCl and/or KCl) concentration gradients in the solutions bathing the membrane. The permeability of the membrane to Na+, K+, and Cl- (expressed as the transference number, T ion) was computed from the steady-state membrane voltage and the activity ratio of the ions in the compartments bathing the membrane. T Na and T K were approximately equal (∼0.8) and considerably greater than T Cl (∼0.2). The ionic transference numbers were independent of temperature, the hydrocarbon solvent, the osmolarity of the solutions bathing the membranes, and the cholesterol content of the membranes, over the range 21–38°C. The high degree of membrane cation selectivity was tentatively attributed to the negatively charged phospholipids (phosphatidylethanolamine and phosphatidylserine) present in the lipid extract.
publisher	The Rockefeller University Press
publishDate	1967
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2225723/
_version_	1611436764234252288

The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids

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