黏液虫巨型轴突的钠通道和钾通道对细胞外pH变化的敏感性。
Sensitivity of the sodium and potassium channels of Myxicola giant axons to changes in external pH.
作者信息
Schauf C L, Davis F A
出版信息
J Gen Physiol. 1976 Feb;67(2):185-95. doi: 10.1085/jgp.67.2.185.
Abstract
Myxicola giant axons were studied using standard voltage-clamp techniques in solutions whose pH values ranged from 3.9 to 10.2. Buffer concentrations of 50 mM or greater were necessary to demonstrate the full effect of pH. In acidic solutions the axon underwent a variable depolarization, and both the sodium and potassium conductances were reversibly depressed with approximate pKa's of 4.8 and 4.4, respectively. The voltage dependence of GNa was only slightly altered by acidic conditions, whereas there occurred large shifts in GK along the voltage axis consistent with a substantial decrease in net negative surface charge in the vicinity of the K+ channels. The sodium and potassium activation rate constants were decreased by acidic conditions, but the results could not be described as a simple translation along the voltage axis.
摘要
使用标准电压钳技术，在pH值范围为3.9至10.2的溶液中研究了黏液虫巨轴突。需要50 mM或更高的缓冲液浓度才能证明pH的全部作用。在酸性溶液中，轴突经历了可变的去极化，钠电导和钾电导均被可逆性抑制，其近似pKa分别为4.8和4.4。酸性条件对钠电导的电压依赖性影响较小，而钾电导沿电压轴发生了较大偏移，这与钾通道附近净负表面电荷的大幅减少一致。酸性条件会降低钠和钾的激活速率常数，但结果不能简单地描述为沿电压轴的平移。
相似文献
1
Sensitivity of the sodium and potassium channels of Myxicola giant axons to changes in external pH.
J Gen Physiol. 1976 Feb;67(2):185-95. doi: 10.1085/jgp.67.2.185.
2
The interactions of calcium with mpyxicola giant axons and a description in terms of a simple surface charge model.
J Physiol. 1975 Jul;248(3):613-24. doi: 10.1113/jphysiol.1975.sp010991.
3
Electrophysiological modifications induced by the fluorescent probe, pyrene, on Myxicola giant axons.
Biochim Biophys Acta. 1980 Apr 24;597(3):622-5. doi: 10.1016/0005-2736(80)90233-3.
4
Magnitude and location of surface charges on Myxicola giant axons.
J Gen Physiol. 1975 Jul;66(1):47-65. doi: 10.1085/jgp.66.1.47.
5
Inhibition of potassium conductance with external tetraethylammonium ion in Myxicola giant axons.
Biophys J. 1980 Dec;32(3):1037-42. doi: 10.1016/S0006-3495(80)85034-X.
6
Actions of the antidepressant drug imipramine on the voltage-clamped Myxicola giant axon.
J Pharmacol Exp Ther. 1975 May;193(2):669-75.
7
Insensitivity of activation delays in potassium and sodium channels to heavy water in Myxicola giant axons.
J Physiol. 1983 Apr;337:173-82. doi: 10.1113/jphysiol.1983.sp014618.
8
Action of extracellular pH on Na+ and K+ membrane currents in the giant axon of Loligo vulgaris.
J Membr Biol. 1978 Nov 8;43(4):295-315. doi: 10.1007/BF01871693.
9
Modifications of sodium channel gating in Myxicola giant axons by deuterium oxide, temperature, and internal cations.
Biophys J. 1979 Aug;27(2):193-208. doi: 10.1016/S0006-3495(79)85211-X.
10
Activation-inactivation coupling in Myxicola giant axons injected with tetraethylammonium.
Biophys J. 1976 Sep;16(9):985-9. doi: 10.1016/S0006-3495(76)85749-9.
引用本文的文献
1
External pH effects on the depolarization-activated K channels in guard cell protoplasts of Vicia faba.
J Gen Physiol. 1994 May;103(5):807-31. doi: 10.1085/jgp.103.5.807.
2
Evidence for negative gating charges in Myxicola axons.
Biophys J. 1983 Jun;42(3):225-31. doi: 10.1016/S0006-3495(83)84390-2.
3
pH aspects of transient changes in conduction velocity in isolated heart fibers after partial replacement of chloride with organic anions.
Pflugers Arch. 1981 Mar;389(3):199-209. doi: 10.1007/BF00584780.
4
The permeability of sodium channels to hydrogen ions in nerve fibres.
Pflugers Arch. 1983 Feb;396(2):163-73. doi: 10.1007/BF00615521.
5
Solvent substitution as a probe of channel gating in Myxicola. Effects of D2O on kinetic properties of drugs that occlude channels.
Biophys J. 1982 Feb;37(2):441-52. doi: 10.1016/S0006-3495(82)84690-0.
6
Separation of potassium and calcium channels in the nerve cell soma membranes.
Neurosci Behav Physiol. 1981 May-Jun;11(3):305-12. doi: 10.1007/BF01184427.
7
Intracellular pH and ionic channels in the Loligo vulgaris giant axon.
Biophys J. 1981 Aug;35(2):393-413. doi: 10.1016/S0006-3495(81)84798-4.
8
Saxitoxin binding in nerves from walking legs of the lobster Homarus americanus. Two classes of receptors.
J Gen Physiol. 1981 Feb;77(2):205-21. doi: 10.1085/jgp.77.2.205.
9
Properties of toxin-resistant sodium channels produced by chemical modification in frog skeletal muscle.
J Physiol. 1980 Aug;305:485-500. doi: 10.1113/jphysiol.1980.sp013377.
10
Asymmetric proton block of inward rectifier K channels in skeletal muscle.
Pflugers Arch. 1984 Aug;401(4):402-7. doi: 10.1007/BF00584343.
本文引用的文献
1
Charges and potentials at the nerve surface. Divalent ions and pH.
J Gen Physiol. 1968 Feb;51(2):221-36. doi: 10.1085/jgp.51.2.221.
2
Effect of surface charge on the steady-state potassium conductance of nodal membrane.
Nature. 1970 Oct 10;228(5267):164-5. doi: 10.1038/228164a0.
3
The effect of reducing extracellular pH on the membrane currents of the ranvier node.
Pflugers Arch. 1969;313(1):80-8. doi: 10.1007/BF00586331.
4
Current- and voltage-clamped studies on Myxicola giant axons. Effect of tetrodotoxin.
J Gen Physiol. 1969 Dec;54(6):730-40. doi: 10.1085/jgp.54.6.730.
5
Evidence against hydrogen-calcium competition model for activation of electrically excitable membranes.
Nat New Biol. 1971 Sep 1;233(35):16-7. doi: 10.1038/newbio233016a0.
6
Inactivation of the sodium current in Myxicola giant axons. Evidence for coupling to the activation process.
J Gen Physiol. 1972 Jun;59(6):659-75. doi: 10.1085/jgp.59.6.659.
7
Temperature dependence of the ionic current kinetics of Myxicola giant axons.
J Physiol. 1973 Nov;235(1):197-205. doi: 10.1113/jphysiol.1973.sp010384.
8
Quantitative description of sodium and potassium currents and computed action potentials in Myxicola giant axons.
J Gen Physiol. 1973 Mar;61(3):361-84. doi: 10.1085/jgp.61.3.361.
9
Specific and unspecific charges at the sodium channels of the nerve membrane.
Pflugers Arch. 1974;351(3):207-29. doi: 10.1007/BF00586919.
10
Ionic blockage of sodium channels in nerve.
J Gen Physiol. 1973 Jun;61(6):687-708. doi: 10.1085/jgp.61.6.687.
Zotero 插件