Analysis of membrane permeability coefficient ratios and internal ion concentrations from a constant field equation

Geduldig, D.

doi:10.1016/0022-5193(68)90005-2

Cited by 14 publications

(7 citation statements)

References 10 publications

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“…A fairly obvious explanation for the additional components is that they represent the effects of some electrogenic ion transport mechanism. The effects of such a mechanism on the Goldman constant field equation have recently been discussed by Geduldig (1968) and by Moreton (1969). Moreton has assumed that an electrogenic sodium pump would contribute an outward current to the currents flowing across the membrane and on this basis he has derived the following form of eqn.…”

Section: Discussionmentioning

confidence: 98%

The resting membrane potential of the somatic muscle cells of Ascaris lumbricoides

Brading¹,

Caldwell²

1971

The Journal of Physiology

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1. The resting membrane potential of Ascaris muscle fibres, which is normally relatively insensitive to ion changes in the medium, has been measured under a wide variety of conditions. 2. The results have been interpreted in terms of a form of the constant field equation containing additional terms for the contribution of ions and charged groups other than potassium, sodium and chloride. 3. Normally the contribution of the additional terms is large and tends to outweigh the contributions of potassium, sodium and chloride. 4. The contribution of the additional terms is considerably reduced in the absence of sodium and in the presence of γ‐amino butyric acid and acetylcholine. 5. It is suggested that the additional terms may represent the contribution of an electrogenic active transport mechanism to the factors determining the membrane potential.

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Section: Discussionmentioning

confidence: 98%

The resting membrane potential of the somatic muscle cells of Ascaris lumbricoides

Brading¹,

Caldwell²

1971

The Journal of Physiology

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“…The GHK equation in the above form neglects the possible complications caused by the effects of electrogenic pumps on the membrane potential. The use of the GHK equation in the presence of an electrogenic pump in the frog muscle was analyzed by Geduldig (1968). His result suggests that if pumps are only "slightly" electrogenic (i.e., less than 10 -11 mol/cmZ/sec) the net diffusion current will not substantially affect the constant field equation.…”

Section: Transmembrane Potentialmentioning

confidence: 99%

Water transport and estimated transmembrane potential during freezing of mouse oocytes

Toner

Cravalho

Armant³

1990

J. Membrain Biol.

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The kinetics of water transport and the changes in transmembrane potential during freezing of mouse oocytes in isotonic phosphate buffered saline (PBS) were simulated using thermodynamic models. The permeability to water at 0 degree C, Lpg, and the activation energy, ELp, of metaphase II mouse oocytes from B6D2F1 mice were determined to be 0.044 +/- 0.008 micron/min-atm and 13.3 +/- 2.5 kcal/mol during freezing at 2 degrees C/min. The inactive cell volume was determined to be 0.214 with a correlation coefficient of 0.995, indicating that the oocytes closely follow the ideal Boyle-van't Hoff relation. The mean value of the oocyte diameter was 79.41 +/- 4.62 microns. These results were used to predict the behavior of mouse oocytes under various freezing conditions. The effect of the cooling rate on the cell volume and cytoplasm undercooling was investigated. The changes in transmembrane potential were also investigated during freezing of mouse oocytes. The computer simulations showed that at the beginning of the freezing process (-1 degrees C), the fast growth of ice in the extracellular solution causes a sharp increase of the membrane potential. It is predicted that the change in membrane potential is substantial for almost all cooling rates. Estimations show that values as high as -90 mV may be reached during freezing. The hyperpolarization of the membrane may cause orientation of the dipoles within the membrane. For membrane proteins with 300 debye dipole moment, the theoretical prediction suggests that the percentage of dipoles aligned with the membrane potential increases from 16% at 0 degrees C prior to freezing to 58% at -8 degrees C after seeding of the external ice followed with a cooling at 120 degrees C/min.

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“…These calculations assume that chloride is distributed in equilibrium with the membrane potential which is nearly the case because of the constant [K]o[C1]o product used. Since a is not zero, the (a[Na] + [K]) [GI] product should be kept constant (Geduldig, 1968). However, the error is only a few per cent.…”

Section: Effects Of Hypertonic Solutions On Mechanical Thresholdmentioning

confidence: 99%

Some Effects of Hypertonic Solutions on Contraction and Excitation-Contraction Coupling in Frog Skeletal Muscles

Gordon

Godt

1970

The Journal of General Physiology

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In frog fast skeletal muscle, we find a decline of twitch, tetanus, and maximum K and caffeine contracture tensions as tonicity of the bathing solution is increased. The decline of tension independent of the method of producing contraction indicates that the major effect of hypertonicity is directly on contractile tension probably because of the increased internal ionic strength. However, there is some apparent disruption of excitation-contraction (E-C) coupling in solutions made three times the normal tonicity (3T solutions) since: (a) in ST solutions tetanic and K contracture tensions decline to zero from a value near the average maximum caffeine contracture tension at this tonicity (10 % of 1T tetanic tension). At this time, caffeine contractures of 10 % of 1T tetanic tension can be elicited; (b) once the K contracture tension has declined, elevated [Ca++]°, 19.8 mM, restores K contracture tension to 13 % of IT tetanic tension. This probable disruption is not caused by changes in mechanical threshold since in Zl" solutions the mechanical threshold is shifted by 12 mv in the hyperpolarizing direction. This is consistent with neutralization of fixed negative charges on the inside of the membrane. The repriming curve is also shifted in the hyperpolarizing direction in 2T solutions. Shifts of the repriming curve coupled with membrane depolarizations in 3T solutions (about 20 my) may produce loss of repriming ability at the resting potential and disruption of E-C coupling.It has been known for over 60 years that hypertonic solutions can decrease contractile tensions in skeletal muscles (Overton, 1902;Ernst, 1926) and that cells m a y be excitable under conditions where tension is vanishingly small (Demoor and Philippson, 1909;Ernst, 1926). Hodgkin and Horowicz (1957) stimulated renewed interest in the effects of hypertonic solutions on excitationcontraction (E-C) coupling in skeletal muscle by showing that bathing a muscle fiber in solutions made 2.5 times the normal tonicity of Ringer solution abolished twitch tension while leaving the action potential virtually unaffected. T h e y also found that tetanic tension was about one-third of that at

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Analysis of membrane permeability coefficient ratios and internal ion concentrations from a constant field equation

Cited by 14 publications

References 10 publications

The resting membrane potential of the somatic muscle cells of Ascaris lumbricoides

The resting membrane potential of the somatic muscle cells of Ascaris lumbricoides

Water transport and estimated transmembrane potential during freezing of mouse oocytes

Some Effects of Hypertonic Solutions on Contraction and Excitation-Contraction Coupling in Frog Skeletal Muscles

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