Summary
The current-voltage curve of theChara membrane was obtained by applying a slow ramp de- and hyperpolarization by use of voltage clamp. By inhibiting the electrogenic pump with 50μm DCCD (dicyclohexylcarbodiimide), theI–V curve approached a steady state within 100 min, which gave thei d -V curve of the passive diffusion channel. Thei p -V curve of the electrogenic pump channel was obtained by subtracting the latter from the former. With the increase of external pH, thei d -V curve showed only a slight change, while thei p -V curve of the pump channel showed almost a parallel shift, in the hyperpolarizing direction, along the voltage axis in the pH range between 6.5 and 7.5. The sigmoidali p -V curve in this pH range could be simulated satisfactorily with the five-state model reported previously (U. Kishimoto, N. Kami-ike, Y. Takeuchi & T. Ohkawa,J. Membrane Biol. 80:175–183, 1984) as well as with a lumped two-state model presented in this report. The analysis based on these models suggests that the electrogenic pump of theChara membrane is mainly a 2H+/1ATP pump. The forward rate constant in the voltage-dependent step increased with the increase of external pH, while the backward one decreased. On the other hand, the forward rate constant in the voltage-independent step remained almost unchanged with the increase of external pH, while the backward one increased markedly. The pump conductance at the resting membrane potential showed either a slight increase or a decrease with the increase of external pH, depending on the sample. Nevertheless, the pump current showed generally a slight increase with the increase of external pH.
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Adrianov, V.K., Vorobieva, I.A., Kurella, G.A. 1968. Investigation of the resting potential ofNitella cells. 2. Effect of pH of medium on resting potential ofNitella cells.Biophyzica 13:396–398
Beilby, M.J. 1984. Current-voltage characteristics of the proton pump atChara plasmalemma: I. pH dependence.J. Membrane Biol. 81:113–125
Bisson, M.A., Walker, N.A. 1980a. The hyperpolarization of theChara membrane at high pH: Effects of external potassium. internal pH, and DCCD.J. Exp. Bot. 32:951–971
Bisson, M.A., Walker, N.A. 1980b. TheChara plasmalemma at high pH. Electrical measurements show rapid specific passive uniport of H+ or OH−.J. Membrane Biol. 56:1–7
Chapman, J.B., Johnson, E.A., Kootsey, J.M. 1983. Electrical and biochemical properties of an enzyme model of the sodium pump.J. Membrane Biol. 74:139–153
Conti, F., De Felice, L.J., Wanke, E. 1975. Potassium and sodium ion current noise in the membrane of the squid giant axon.J. Physiol. (London) 248:45–82
Fujii, S., Shimmen, T., Tazawa, M. 1979. Effect of intracellular pH on the light-induced potential change and electrogenic activity in tonoplast-free cells ofChara australis.Plant Cell Physiol. 20:1315–1328
Hansen, U.-P., Gradmann, D., Sanders, D., Slayman, C.L. 1981. Interpretation of current-voltage relationships for “active” ion transport systems: I. Steady-state reaction-kinetic analysis of class-I mechanisms.J. Membrane Biol. 63:165–190
Kawamura, G., Shimmen, T., Tazawa, M. 1980. Dependence of the membrane potential ofChara cells on external pH in the presence and absence of internal adenosinetriphosphate.Planta 149:213–218
Keifer, D.W., Spanswick, R.M. 1978. Activity of the electrogenic pump inChara corallina as inferred from measurements of the membrane potential, conductance, and potassium permeability.Plant Physiol. 62:653–661
Kishimoto, U. 1959. Electrical characteristics ofChara corallina.Annu. Rep. Sci. Works (Fac. Sci., Osaka University) 7:115–146
Kishimoto, U., Kami-ike, N., Takeuchi, Y. 1980. The role of electrogenic pump inChara corallina.J. Membrane Biol. 55:149–156
Kishimoto, U., Kami-ike, N., Takeuchi, Y. 1981. A quantitative expression of the electrogenic pump and its possible role in the excitation ofChara internodes.In: The Biophysical Approach to Excitable Systems. W. J. Adelman, Jr. and D. E. Goldman, editors. pp. 165–181. Plenum, New York
Kishimoto, U., Kami-ike, N., Takeuchi, Y., Ohkawa, T. 1982. An improved method for determining the ionic conductance and capacitance of the membrane ofChara corallina.Plant Cell Physiol. 23:1041–1054
Kishimoto, U., Kami-ike, N., Takeuchi, Y., Ohkawa, T. 1984. A kinetic analysis of the electrogenic pump ofChara corallina: I. Inhibition of the pump by DCCD.J. Membrane Biol. 80:175–183
Kitasato, H. 1968. The influence of H+ on the membrane potential and ion fluxes ofNitella.J. Gen. Physiol. 52:60–87
Kotani, T. 1979. A modification of Powell's method for minimization of nonlinear functions.Computer Center News (Osaka University) 32:27–47
Lannoye, R.J., Tarr, S.E., Dainty, J. 1970. The effects of pH on the ionic and electric properties of the internodal cells ofChara australis.J. Exp. Bot. 21:543–551
Läuger, P. 1979. The channel mechanism for electrogenic ion pumps.Biochim. Biophys. Acta 552:143–161
Lucas, W.J., Keifer, D.W., Sanders, D. 1983. Bicarbonate transport inChara corallina: Evidence for cotransport of HCO3 with H+.J. Membrane Biol. 73:263–274
Ohkawa, T., Kishimoto, U. 1974. The electromotive force of theChara membrane during the hyperpolarizing response.Plant Cell Physiol. 15:1039–1054
Ohkawa, T., Kishimoto, U. 1977. Breakdown phenomena in theChara membrane.Plant Cell Physiol. 18:67–80
Oosawa, F., Hayashi, S. 1983. Coupling between flagellar motor rotation and proton flux in bacteria.J. Phys. Soc. Japan 52:4019–4028
Powell, M.J.D. 1965. A method of minimizing a sum of squares of nonlinear functions without calculating derivatives.Computer J. 7:303–307
Rent, R.K., Johnson, R.A., Barr, C.E. 1972. Net H+ influx inNitella clavata.J. Membrane Biol. 7:231–244
Richards, J.L., Hope, A.B. 1974. The role of protons in determining membrane electrical characteristics inChara corallina.J. Membrane Biol. 16:121–144
Saito, K., Senda, K. 1973. The effect of external pH on the membrane potential ofNitella and its linkage to metabolism.Plant Cell Physiol. 14:1045–1052
Saito, K., Senda, K. 1974. The electrogenic ion pump revealed by the external pH effect on the membrane potential ofNitella. Influence of external ions and electrical current on the pH effect.Plant Cell Physiol. 15:1007–1016
Sanders, D., Hansen, U-P., Slayman, C.L. 1981. Role of the plasma membrane proton pump in pH regulation in non-animal cells.Proc. Natl. Acad. Sci. USA 78:5903–5907
Sanders, D., Slayman, C.L. 1982. Control of intracellular pH.J. Gen. Physiol. 80:377–402
Shimmen, T., Tazawa, M. 1980. Dependency of H+ efflux on ATP in cells ofChara australis.Plant Cell Physiol. 21:1007–1013
Smith, F.A., Raven, J.A. 1979. Intracellular pH and its regulation.Annu. Rev. Plant Physiol. 35:289–311
Smith, F.A., Walker, N.A. 1976. Chloride transport inChara corallina and the electrochemical potential difference for hydrogen ions.J. Exp. Bot. 27:451–459
Spanswick, R.M. 1972. Evidence for an electrogenic pump inNitella translucens. I. The effects of pH, K+, Na+, light and temperature on the membrane potential and resistance.Biochim. Biophys. Acta 288:73–89
Spanswick, R.M., Miller, A.G. 1977. Measurement of the cytoplasmic pH inNitella translucens.Plant Physiol. 59:664–666
Steinmetz, P.R., Anderson, O.S. 1982. Electrogenic proton transport in epithelial membranes.J. Membrane Biol. 65:155–174
Takeuchi, Y., Kishimoto, U. 1983. Changes of adenine nucleotide levels inChara internodes during metabolic inhibition.Plant Cell Biol. 2:1401–1409
Tazawa, M., Shimmen, T. 1982. Artificial control of cytoplasmic pH and its bearing on cytoplasmic streaming, electrogenesis and excitability ofCharaceae cells.Bot. Mag. Tokyo 95:147–154
Walker, N.A. 1980. The transport systems of charophyte and chlorophyte giant algae and their integration into modes of behaviour.In: Plant Membrane Transport: Current Conceptual Issues. R. M. Spanswick, W. J. Lucas and J. Dainty, editors. pp. 287–300. Elsevier/North-Holland, Amsterdam
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Takeuchi, Y., Kishimoto, U., Ohkawa, T. et al. A kinetic analysis of the electrogenic pump ofChara corallina: II. Dependence of the pump activity on external pH. J. Membrain Biol. 86, 17–26 (1985). https://doi.org/10.1007/BF01871606
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DOI: https://doi.org/10.1007/BF01871606