Screening of membrane surface charges by divalent cations: an atomic representation

D'Arrigo, Joseph

doi:10.1152/ajpcell.1978.235.3.c109

Cited by 68 publications

(41 citation statements)

References 26 publications

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“…The dependence of surface potential on cation concentration in cardiac inward-rectifier K channels is comparable to crayfish axon Na channels (D'Arrigo, 1978), but it is significantly greater than for Na and K channels in virtually all other experiments (Gilbert & Ehrenstein, 1983). Greater sensitivity suggests that electrostatic repulsion helps maintain the open channel and that decreasing the surface charge results in partial collapse of the pore.…”

Section: Discussionmentioning

confidence: 82%

Surface charge near the cardiac inward-rectifier channel measured from single-channel conductance

Kell

DeFelice

1988

J. Membrain Biol.

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The conductance of a channel to permeable ions depends on the number of ions near the mouth of the pore. Surface charge controls the local concentration, and impermeable cations can modify this charge. Correlating channel conductance with the concentration of impermeable cations therefore determines the local charge near the open pore. This paper presents data from cell-attached patches on embryonic chick ventricle cells, and it uses the conductance of inward-rectifier channels in the patch (in 100 mM K, with various concentrations of Na, Ca, Ba, and Mg) to estimate the local surface potential. The results indicate the presence of ionized residues near the mouth of the channel. Using the Boltzmann equation and the Gouy-Chapman relation, the surface potential due to these residues (in 100K/33Na/0Ca/0Ba/0Mg) is -40 mV, and the charge density is -0.25 e/nm2.

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Section: Discussionmentioning

confidence: 82%

Surface charge near the cardiac inward-rectifier channel measured from single-channel conductance

Kell

DeFelice

1988

J. Membrain Biol.

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“…As stated above, the effects of mucosal solution pH changes and the effects of high and low ionic strength solutions on apparent K permeability support the notion that the apical membrane of Necturus gallbladder has a net negative surface charge. One would therefore expect a screening effect of divalent cations at the concentrations employed in this study (D'Arrigo, 1978). The behavior of Ba a+ and Sr z+ was different from those of Mg 2+, and Ca 2+.…”

Section: Mechanisms Of Effects Of Divalent Cations On Apical Membrane Pkmentioning

confidence: 86%

Mechanisms of cation permeation across apical cell membrane ofNecturus gallbladder: Effects of luminal pH and divalent cations on K+ and Na+ permeability

1981

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Conventional microelectrode techniques were combined with unilateral mucosal ionic substitutions to determine the effects of luminal pH and luminal alkali-earth cation concentrations on apical membrane cation permeability in Necturus gallbladder epithelium. Acidification of the mucosal solution caused reversible depolarization of both cell membranes and increase of transepithelial resistance. Low pH media also caused: (a) reduction of the apical membrane depolarization induced by high K, and (b) increase of the apical membrane hyperpolarization produced by Na replacement with Li or N-Methyl-D-glucamine. These results, in conjunction with estimates of cell membrane conductances, indicate that acidification of the luminal solution produces a reduction of apical membrane K permeability (PK). Addition of alkali earth cations (Mg2+, Ca2+, Sr2+, or Ba2+) produced cell membrane depolarization, increase of relative resistance of the luminal membrane and reduction of the apical membrane potential change produced by a high-K mucosal medium. These results, as those produced by low pH, can be explained by a reduction of apical membrane PK. The effects of Ba2+ on membrane potential and relative apical membrane PK were larger than those of all other four cations at all concentrations tested (1-10 mM). The effect of Sr2+ was significantly larger than those of Mg2+ and Ca2+ at 10 mM, but not different at 5 mM. The reduction of PK produced by mucosal acidification appears to be mediated by: (a) nonspecific titration of membrane fixed negative charges, and (b) an effect of luminal proton activity on the apical K channel. Divalent cations reduce apical membrane PK probably by screening negative surface charges. The larger magnitude of the effects of Ba2+ and Sr2+ can be explained by binding to membrane sites, in the surface or in the K channel, in addition to their screening effect. We suggest that the action of luminal pH on K secretion in some segments of the renal tubule could be mediated in part by this pH-dependent K permeability of the luminal membrane.

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“…Typically, these results have been interpreted as being due to changes in the hypothetical surface potential, which is presumed to arise from fixed negative charges at the membrane surface . This hypothetical change in surface potential was attributed to the divalent cations specifically binding to the fixed charges, to the divalent cations "screening" the fixed charges (for detailed discussions see Grahame, 1947, andD'Arrigo, 1978), or to a combination of both mechanisms (Frankenhaeuser and Hodgkin, 1957 ;Gilbert and Ehrenstein, 1969 ;McLaughlin et al ., 1971McLaughlin et al ., , 1981Hille et al ., 1975). In any case, increased divalent ion concentration was hypothesized to reduce the effective surface potential and thereby produce a hyperpolarizing offset in the potential sensed by the gating machinery located within the membrane.…”

Section: Introductionmentioning

confidence: 99%

Simple shifts in the voltage dependence of sodium channel gating caused by divalent cations.

Hahin¹,

Campbell²

1983

The Journal of General Physiology

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The effect of elevated divalent cation concentration on the kinetics of sodium ionic and gating currents was studied in voltage-clamped frog skeletal muscle fibers . Raising the Ca concentration from 2 to 40 mM resulted in nearly identical 30-mV shifts in the time courses of activation, inactivation, tail current decay, and ON and OFF gating currents, and in the steady state levels of inactivation, charge immobilization, and charge vs. voltage. Adding 38 mM Mg to the 2 mM Ca bathing a fiber produced a smaller shift of -20 mV in gating current kinetics and the charge vs . voltage relationship. The results with both Ca and Mg are consistent with the hypothesis that elevated concentrations of these alkali earth cations alter Na channel gating by changing the membrane surface potential. The different shifts produced by Ca and Mg are consistent with the hypothesis that the two ions bind to fixed membrane surface charges with different affinities, in addition to possible screening.

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Screening of membrane surface charges by divalent cations: an atomic representation

Cited by 68 publications

References 26 publications

Surface charge near the cardiac inward-rectifier channel measured from single-channel conductance

Surface charge near the cardiac inward-rectifier channel measured from single-channel conductance

Mechanisms of cation permeation across apical cell membrane ofNecturus gallbladder: Effects of luminal pH and divalent cations on K+ and Na+ permeability

Simple shifts in the voltage dependence of sodium channel gating caused by divalent cations.

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