A Study of Lipid Bilayer Membrane Stability Using Precise Measurements of Specific Capacitance Export

@article{citeulike:3762188, abstract = {A method is described for measuring the specific capacitance (Cm) of lipid bilayer membranes with an estimated experimental error of only 1\%. The gross capacitance was measured with an AC Wheatstone bridge and a photographic technique was used to determine the area of thin membrane. The results of measurements on oxidized cholesterol-decane membranes formed in 1 x 10-2 M KCl show that Cm depends upon temperature, voltage, time, and the age of the bulk membrane solutions. For a freshly thinned membrane (from 5 week old solution), Cm increases exponentially from an initial value of 0.432 {+/-}0.021 (SD) {micro}F/cm2 with a time constant of [\~{}]15 min. A 100 mv potential applied across the membrane for 10-20 min prior to making measurements eliminated this time dependence and produced final-state membranes. Cm of final-state membranes depends upon applied voltage (Va) and obeys the equation Cm = C0 + {beta}Va2 where Va [\~{}=] VDC + VrmsAC. C0 and {beta} depend upon temperature; C0 decreases linearly with temperature while {beta} increases linearly. At 20{degrees}C, C0 = 0.559 {+/-}0.01 (SD) {micro}F/cm2 and {beta} = 0.0123 {+/-}0.0036 (SD) ({micro}F/cm2)/(mv2) and at 34{degrees}C, C0 = 0.472 {+/-}0.01 and {beta} = 0.0382 {+/-}0.0039. These variations in Cm are interpreted as resulting from thickness changes. The possibility that they result from diffuse layer and/or membrane dielectric phenomena is discussed and found to be unlikely. The results are discussed in terms of membrane stability by constructing hypothetical potential energy vs. thickness curves.}, author = {White, Stephen H.}, citeulike-article-id = {3762188}, citeulike-linkout-0 = {http://www.biophysj.org/cgi/content/abstract/10/12/1127?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&titleabstract=membrane+capacitance+&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/5489777}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=5489777}, journal = {Biophys. J.}, keywords = {bilayer, capacitance, membrane, planar, white70pdf}, month = {December}, number = {12}, pages = {1127--1148}, posted-at = {2008-12-09 18:37:17}, priority = {2}, title = {A Study of Lipid Bilayer Membrane Stability Using Precise Measurements of Specific Capacitance}, url = {http://www.biophysj.org/cgi/content/abstract/10/12/1127?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&titleabstract=membrane+capacitance+&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT}, volume = {10}, year = {1970} }

TY - JOUR ID - citeulike:3762188 L3 - citeulike-article-id:3762188 N2 - A method is described for measuring the specific capacitance (Cm) of lipid bilayer membranes with an estimated experimental error of only 1%. The gross capacitance was measured with an AC Wheatstone bridge and a photographic technique was used to determine the area of thin membrane. The results of measurements on oxidized cholesterol-decane membranes formed in 1 x 10-2 M KCl show that Cm depends upon temperature, voltage, time, and the age of the bulk membrane solutions. For a freshly thinned membrane (from 5 week old solution), Cm increases exponentially from an initial value of 0.432 {+/-}0.021 (SD) {micro}F/cm2 with a time constant of [~]15 min. A 100 mv potential applied across the membrane for 10-20 min prior to making measurements eliminated this time dependence and produced final-state membranes. Cm of final-state membranes depends upon applied voltage (Va) and obeys the equation Cm = C0 + {beta}Va2 where Va [~=] VDC + VrmsAC. C0 and {beta} depend upon temperature; C0 decreases linearly with temperature while {beta} increases linearly. At 20{degrees}C, C0 = 0.559 {+/-}0.01 (SD) {micro}F/cm2 and {beta} = 0.0123 {+/-}0.0036 (SD) ({micro}F/cm2)/(mv2) and at 34{degrees}C, C0 = 0.472 {+/-}0.01 and {beta} = 0.0382 {+/-}0.0039. These variations in Cm are interpreted as resulting from thickness changes. The possibility that they result from diffuse layer and/or membrane dielectric phenomena is discussed and found to be unlikely. The results are discussed in terms of membrane stability by constructing hypothetical potential energy vs. thickness curves. IS - 12 JF - Biophys. J. EP - 1148 TI - A Study of Lipid Bilayer Membrane Stability Using Precise Measurements of Specific Capacitance VL - 10 SP - 1127 KW - bilayer KW - capacitance KW - membrane KW - planar KW - white70pdf AU - White, Stephen PY - 1970/12/01/ UR - http://www.biophysj.org/cgi/content/abstract/10/12/1127?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&titleabstract=membrane+capacitance+&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT ER -