Abstract
Patch currents in the cell attached-mode and action potentials (AP) have been recorded simultaneously in internodal cells of Chara corallina. The action potentials are closely correlated with transient patch currents. With pipettes containing either 50 mm CaCl2 or 100 nm KCl plus 1 or 5 mm CaCl2, these transients measured up to 100 to 200 pA per patch at zero mV. Transients had a mean duration (time during which the current was ≥ half maximum peak amplitude) of about 1 sec, a maximum slope for current rising of about 400 pA sec−1 and a maximum rate of about 100 pA sec−1 for current decay, with no obvious effect of external Ca2+ on either of these parameters. In well-resolved recordings of current transients triggered by an action potential (AP), activities of two types of Cl−-conducting channels (15 and 38 pS) have been identified. Since activity of these channels was only observed during action potentials but not upon positive voltage steps, these channels are not directly voltage gated but point to a cytoplasmic gating factor which accumulates during excitation and propagates from excited areas to the patch. A K+-conducting channel (40 pS) could be identified as well during an AP, when 100 mm KCl was in the pipette solution. The activity of this channel relaxed at the end of the APs with a time constant of about 3 sec. Stimulated activity of this channel is understood to cause the repolarization overshoot during the final phase of the action potential, whereas the transient activation of the Cl− channels determines the fast voltage changes of the action potential.
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Armstrong, C.M., Binstock, L. 1965. Anomalous rectification in the squid giant axon injected with tetraethylammonium chloride. J. Gen. Physiol. 48:859–872
Azimov, R.R., Geletyuk, V.l., Berestovskii, G.N. 1984. Single potential-dependent K+ channel of the cells of the alga Nitellopsis obtusa. Biofizika 32:79–84
Beilby, M.J., Blatt, M.R. 1986. Simultaneous measurements of cytoplasmic K+ concentration and plasma membrane electrical parameters in single samples of Chara corallina. Plant Physiol. 82:417–422
Beilby, M.J., Coster, H.G.L. 1979a. The action potential in Chara corallina II. Two activation-inactivation transients in voltage clamps of the plasmalemma. Aust. J. Plant Physiol. 6:323–325
Beilby, M.J., Coster, H.G.L. 1979b. The action potential in Chara corallina III. The Hodgkin-Huxley parameters for the plasmalemma. Aust. J. Plant Physiol. 6:337–353
Beilby, M.J., Mimura, T., Shimmen, T. 1993. The proton pump, high pH channels, and excitation: voltage clamp studies of intact and perfused cells of Nitellopsis obtusa. Protoplasma 175:144–152
Berestovskii, G.N., Zherelova, O.M., Kataev, A.A. 1987. Ionic channels in characean algal cells. Biofizika 32:1011–1027
Coleman, H.A. 1986. Chloride currents in Chara—A patch-clamp study. J. Membrane Biol. 93:55–61
Findlay, G.P., Hope, A.B. 1964. Ionic relations of cells of Chara australis. VII. The separate electrical characteristics of the plasmalemma and tonoplast. Austr. J. Biol. Sci. 17:62–77
Fischmeister, R., DeFelice, L.J., Ayer, R.K., Levi, R., DeHaan, R.L. 1984. Channel currents during spontaneous action potentials in embryonic chick heart cells. Biophys. J. 46:267–272
Gaffey, C.T., Mullins, L.J. 1958. Ion fluxes during the action potential in Chara. J. Physiol. 144:505–524
Hille, B. 1967. The selective inhibition of delayed potassium currents in nerve by tetraethylammonium ion. J. Gen. Physiol. 50:1287–1302
Hope, A.B., Findlay, G.P. 1964. The action potential in Chara. Plant Cell Physiol. 5:377–379
Kataev, A.A., Zherelova, O.M., Berestovskii, G.N. 1988. Effect of charged local anaesthetics on inactivation of Ca2+-activated Cl− channels of Characean algae. Biofizika 33:1076–1084
Katsuhara, M., Mimura, T., Tazawa, M. 1990. ATP-regulated ion channels in the plasma membrane of a Characeae alga Nitellopsis obtusa. Plant Physiol. 93:343–346
Kikuyama, M. 1986. Ion effluxes during excitation of Characeae. Plant Cell Physiol. 27:1213–1216
Kikuyama, M., Oda, K., Shimmen, T., Hayama, T., Tazawa, M. 1984. Potassium and chloride efflux during excitation of Characean cells. Plant Cell Physiol 25:965–974
Kikuyama, M., Simada, K., Hiramoto, Y. 1993. Cessation of cytoplasmic streaming follows an increase of cytoplasmic Ca2+ during action potential in Nitella. Protoplasma 174:142–146
Kishimoto, U. 1966. Repetitive action potentials in Nitella internodes. Plant Cell Physiol. 7:547–558
Koppenhöfer, E. 1972. Die Wirkung von Kupfer, TTX, Cocain und TEA auf das Ruhe- und Aktionspotential von Nitella. Pfluegers Arch. 336:299–309
Laver, D.R. 1991. A surgical method for accessing the plasma membrane of Chara australis. Protoplasma 161:79–84
Lunevsky, V.Z., Zherelova, O.M., Vostrikov, I.Y., Berestovskii, G.N. 1983. Excitation of Characeae cell membranes as a result of activation of calcium and chloride channels. J. Membrane Biol. 72:43–58
Mazzanti, M., DeFelice, L.J. 1988. K channel kinetics during the spontaneous heart beat in embryonic chick ventricle cells. Biophys. J. 54:1139–1148
Mazzanti, M., DeFelice, L.J. 1990. Ca channel gating during cardiac action potentials. Biophys. J. 58:1059–1065
Miller, A.J., Sanders, D. 1987. Depletion of cytosolic free calcium induced by photosynthesis. Nature 326:397–400
Milton, R.L., Cadwell, J.H. 1990. How do patch clamp seals form? Pfluegers Arch. 416:758–765
Oda, K. 1976. Simultaneous recording of potassium and chloride efflux during an action potential in Chara corallina. Plant Cell Physiol. 17:1085–1088
Okihara, K., Ohkawa, T.A., Kasai, M. 1993. Effect of calmodulin on Ca2+-dependent Cl−-sensitive anion channels in the Chara plasmalemma: a patch clamp study. Plant Cell Physiol. 34:75–82
Okihara, K., Kiyosawa, K. 1988. Ion composition of the Chara internode. Plant Cell Physiol. 29:21–25
Okihara, K., Ohkawa, T., Tsutsui, I., Kasai, M. 1991. A calcium-dependent and voltage-dependent chloride-sensitive anion channel in the Chara plasmalemma: a patch-clamp study. Plant Cell Physiol. 32:593–602
Robinson, R.A., Stokes, R.H. 1968. Electrolyte Solutions. Butter worth Scientific Publications, London
Reid, R.J., Tester, M. 1992. Measurements of Ca2+ fluxes in intact plant cells. Philos. Trans. R. Soc. Lond. B. Biol. Sci. 338:73–82
Shiina, T., Tazawa, M. 1987. Demonstration and characterization of Ca2+ channel in tonoplast free cells of Nitellopsis obtusa. J. Membrane Biol. 96:263–276
Shiina, T., Wayne, R., Tung, H.Y.L., Tazawa, M. 1988. Possible involvement of protein phosphorylation/dephosphorylation in the modulation of Ca2+ channel in tonoplast-free cells of Nitellopsis. J. Membrane Biol. 102:255–264
Shimmen, T., Kikuyama, M., Tazawa, M. 1976. Demonstration of two stable potential states of plasmalemma of Chara without tonoplast. J. Membrane Biol. 30:249–270
Shimmen, T., Tazawa, M. 1983, Activation of K+-channel in membrane excitation of Nitella axilliformis. Plant Cell Physiol. 24: 1511–1524
Tester, M. 1990. Plant ion channels: whole-cell and single-channel studies. New Phytol. 114:305–340
Thiel, G., Homann, U., Gradmann, D. 1993. Microscopic elements of electrical excitation in Chara: Transient activity of Cl− channels in the plasma membrane. J. Membrane Biol. 134:53–66
Thiel, G., MacRobbie, E.A.C., Hanke, D.E. 1990. Raising the intra cellular level of inositol 1,4,5-trisphosphate changes plasma membrane ion transport in Characean algae. EMBO J. 9:1737–1741
Tsutsui, I., Ohkawa, T., Nagai, R., Kishimoto, U. 1987. Role of calcium ion in the excitability and electrogenic pump activity of the Chara corallina membrane: I. Effects of La3+, verapamil, EGTA, W-7 and TFP on the action potential. J. Membrane Biol. 96:65–74
Williamson, R.E., Ashley, C.C. 1982. Free Ca2+ and cytoplasmic streaming in the alga Chara. Nature 296:647–651
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The financial support by the Deutsche Forschungsgemeinschaft is gratefully acknowledged. The authors thank Prof. D. Gradmann for constructive and stimulating criticism and J. Blatt for help in preparing the manuscript.
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Homann, U., Thiel, G. Cl− and K+ channel currents during the action potential in Chara. simultaneous recording of membrane voltage and patch currents. J. Membarin Biol. 141, 297–309 (1994). https://doi.org/10.1007/BF00235139
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DOI: https://doi.org/10.1007/BF00235139