X-Ray diffraction measurements of dipalmitoylphosphatidylcholine as a function of pressure

Stamatoff, J.; Guillon, Daniel; Powers, Linda S.; Cladis, P. E.; Aadsen, D.

doi:10.1016/0006-291x(78)91221-4

Cited by 65 publications

(26 citation statements)

References 6 publications

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“…The increase in q with potential is also reflected in a small increase in the melting temperature of DPPC. A similar effect on DPPC phase transition was also observed by X-ray diffraction upon application of pressure [51].…”

Section: Discussionsupporting

confidence: 75%

“…This large difference in A V* values could be partially accounted for by the fact that the pressure associated with membrane potential is vertical to the lipid-bilayer, where the compressibility is much smaller than the lateral compressibility [51]. Hydrostatic pressure, on the other hand exerts its effect mostly through lateral compression [51]. The interpretations given above are all based on simple statistical assumptions analogous to the Boltzmann distribution.…”

Section: ~E=0mentioning

confidence: 96%

“…It is noteworthy that in a recent study, where the dependence of lipid microviscosity on hydrostatic pressure was analyzed, it was found that AV* for egg-PC is only 22cm3/mole (in preparation). This large difference in A V* values could be partially accounted for by the fact that the pressure associated with membrane potential is vertical to the lipid-bilayer, where the compressibility is much smaller than the lateral compressibility [51]. Hydrostatic pressure, on the other hand exerts its effect mostly through lateral compression [51].…”

Section: ~E=0mentioning

confidence: 98%

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Increase in lipid microviscosity of unilamellar vesicles upon the creation of transmembrane potential

1982

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Diffusion potential of potassium ions was found in unilamellar vesicles of phosphatidyl choline. The vesicles, which included potassium sulfate buffered with potassium phosphate were diluted into an analogous salt solution made of sodium sulfate and sodium phosphate. The diffusion potential was created by the addition of the potassium-ionophore, valinomycin. The change in lipid microviscosity, ensuing the formation of membrane potential, was measured by the conventional method of fluorescence depolarization with 1,6-diphenyl-1,3,5-hexatriene as a probe. Lipid microviscosity was found to increase with membrane potential in a nonlinear manner, irrespective of the potential direction. Two tentative interpretations are proposed for this observation. The first assumes that the membrane potential imposes an energy barrier on the lipid flow which can be treated in terms of Boltzmann-distribution. The other interpretation assumes a decrease in lipid-free volume due to the pressure induced by the electrical potential. Since increase in lipid viscosity can reduce lateral and rotational motions, as well as increase exposure of functional membrane proteins, physiological effects induced by transmembrane potential could be associated with such dynamic changes.

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Section: Discussionsupporting

confidence: 75%

Section: ~E=0mentioning

confidence: 96%

Section: ~E=0mentioning

confidence: 98%

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Increase in lipid microviscosity of unilamellar vesicles upon the creation of transmembrane potential

1982

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“…An upper limit to the change in membrane capacitance can be set at about 3% for 62 MPa, based upon the accuracy of reading our Polaroid records. Thus, a possible difference between the lateral and perpendicular compressibility of the lipid bilayer matrix of the axon membrane (Stamatoff et al, 1978), should lie within this limit. This result, and the apparent absence of discontinuities in the changes produced by pressures upon the active ionic currents, suggest that these changes do not involve abrupt modifications of the nerve membrane structure.…”

Section: Discussionmentioning

confidence: 98%

Pressure dependence of the sodium currents of squid giant axon

et al. 1982

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Summary. The effects of hydrostatic pressures up to 62 MPa upon the voltage-clamp currents of intact squid giant axons were measured using mineral oil as the pressure transmitting medium. The membrane resistance and capacitance were not appreciably affected over the whole range of pressures explored. The predominant effect of pressure is to slow the overall kinetics of the voltage-clamp currents 9 Both the early (Na) currents and the delayed (K) ones were slowed down by approximately the same time scale factor, which was in the range of 2 to 3 when pressure was increased from atmospheric to 62 MPa.Finer details of the effects, most evident at moderate depolarizations, are: the apparent initial delay in the turn-on of Na currents is increased by pressure less than is the phase of steepest time variation, and the later decay is slowed more than is the rising phase. The initial time course of the currents at high pressures can be made to overlap with that at normal pressure by a constant time compression factor, Ore, together with a small, voltage-dependent delay 9In a given axon, Om was fairly independent of voltage, and it increased exponentially with pressure according to an apparent activation volume, A V • ranging between 32 and 40 cmJ/mole. A V • tended to decrease with increasing temperature. Contrary to what is observed for moderate or large depolarizations, the kinetics of Na inactivation produced by conditioning prepulses of -50 or -60 mV was little affected over the whole range of pressures explored.Inferences about the pressure dependence of the steady-state Na activation were made from the comparison of the plots of early peak currents, Ip, versus membrane potential, E. The Na reversal potential, ENd, and the slope of the plots near EN, did not change significantly with pressure, but the peak Na conductance vs. E relationship was shifted by about + 9 mV upon increasing pressure to 62 MPa. Steady-state Na inactivation, h| was slightly affected by pressure. At 62 MPa the midpoint potential of the h~(E) curve, Eh, was shifted negatively by about 4 mV, while the slope at Eh decreased by about 38%.Under the tentative assumption that pressure directly affects the gating of Na channels, the Na activation data follows a simple Hodgkin-Huxley scheme if the opening of an m gate involves an activation volume of about 58 A_ 3 and a net volume increase of about 26 A 3. However, a self-consistent description of the totality of the effects of pressure on Na inactivation cannot be obtained within a similar simple context.

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“…Such studies have concentrated on a few members of phosphatidylcholines containing two identical linear saturated fatty acyl chains and the thermotropic phase behavior of some phosphatidylcholines (especially dipalmitoylphosphatidylcholine, DPPC) has been relatively well understood. The succeeding high-pressure studies on the DPPC bilayer membrane have been performed with various physical techniques including electron spin resonance [10], dilatometry [11,12], calorimetry [13,14], X-ray diffraction [15], dynamic light scattering [16], Raman spectroscopy [17,18], FT-IR [19], neutron diffraction [20,21], light transmittance [22,23] and NMR [24 -26]. These measurements have revealed that the temperature of main transition from the gel phase to the liquid crystalline phase is elevated linearly by applying pressure.…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced phase transitions of lipid bilayers observed by fluorescent probes Prodan and Laurdan

Kusube

Tamai

Matsuki

et al. 2005

Biophysical Chemistry

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X-Ray diffraction measurements of dipalmitoylphosphatidylcholine as a function of pressure

Cited by 65 publications

References 6 publications

Increase in lipid microviscosity of unilamellar vesicles upon the creation of transmembrane potential

Increase in lipid microviscosity of unilamellar vesicles upon the creation of transmembrane potential

Pressure dependence of the sodium currents of squid giant axon

Pressure-induced phase transitions of lipid bilayers observed by fluorescent probes Prodan and Laurdan

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