Abstract
Voltage clamp experiments were performed on single myelinated nerve fibres of the frogRana esculenta to study the influence of internally applied Ba on the potassium outward current IK. Potassium currents of Ba-treated fibres decay rapidly during 30 ms depolarizations of more than 60 mV. The time constant τ of decay and the steady state potassium current IKss are strongly voltage dependent. The equilibrium dissociation constant K of the Ba-receptor complex decreases e-fold for a 39 mV change of potential. The analysis suggests that the binding site is located at 30% of the membrane field seen from the inside of the axon.
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Århem P (1976) Diffusion of sodium in axoplasm of myelinated nerve fibre. Potential clamp analysis. Acta Physiol Scand 97:415–425
Århem P (1980) Effects of rubidium, caesium, strontium, barium and lanthanum on ionic currents in myelinated nerve fibres of Xenopus laevis. Acta Physiol Scand 108:7–16
Armstrong CM, Hille B (1972) The inner quaternary ammonium ion receptor in potassium channels of the node of Ranvier. J Gen Physiol 59:388–400
Armstrong CM, Taylor SR (1980) Interaction of barium ions with potassium channels in squid giant axons. Biophys J 30:473–488
Bergman C (1970) Increase of sodium concentration near the inner surface of the nodal membrane. Pflügers Arch 317:287–302
Bezanilla F, Armstrong CM (1972) Negative conductance caused by entry of sodium and cesium ions into the potassium channels of squid giant axons. J Gen Physiol 60:588–608
Eaton DC, Brodwick MS (1980) Effects of barium on the potassium conductance of squid axon. J Gen Physiol 75:727–750
Frankenhaeuser B (1963) A quantitative description of potassium currents in myelinated nerve fibres of Xenopus laevis. J Physiol 169:424–430
French RJ, Wells JB (1977) Sodium ions as charge carriers in the K+ channel of the squid giant axon. J Gen Physiol 70:707–724
Hille B (1975) Ionic selectivity of Na and K channels of nerve membranes. In: Eisenman G (ed) Membranes III. Dekker, New York, pp 256–323
Nonner W (1969) A new voltage clamp method for Ranvier nodes. Pflügers Arch 309:177–192
Palti Y, Gold R, Stämpfli R (1979) Diffusion of ions in myelinated nerve fibres. Biophys J 25:17–31
Schwarz JR, Vogel W (1971) Potassium inactivation in single myelinated nerve fibres of Xenopus laevis. Pflügers Arch 330:61–73
Schwarz JR, Ulbricht W, Wagner HH (1973) The rate of action of tetrodotoxin on myelinated nerve fibres of Xenopus laevis and Rana esculenta. J Physiol 233:167–194
Sperelakis N, Schneider M, Harris EJ (1967) Decreased K conductance produced by Ba++ in frog sartorius fibres. J Gen Physiol 50:1565–1583
Stämpfli R, Hille B (1976) Electrophysiology of the peripheral myelinated nerve. In: Llinas R, Precht W (eds) Frog neurobiology. Springer, Berlin Heidlberg New York, pp 3–32
Werman R, Grundfest H (1961) Graded and all-or-none electrogenesis in the arthropod muscle. II. The effects of alkali-earth and onium ions on lobster muscle fibers. J Gen Physiol 44:997–1027
Woodhull AM (1973) Ionic blockage of sodium channels in nerve. J Gen Physiol 61:687–708
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Woll, K.H. The effect of internal barium on the K current of the node of Ranvier. Pflugers Arch. 393, 318–321 (1982). https://doi.org/10.1007/BF00581417
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DOI: https://doi.org/10.1007/BF00581417