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. 1995 Apr 1;105(4):441–462. doi: 10.1085/jgp.105.4.441

Surface charge and calcium channel saturation in bullfrog sympathetic neurons

PMCID: PMC2216931  PMID: 7608653

Abstract

Currents carried by Ba2+ through calcium channels were recorded in the whole-cell configuration in isolated frog sympathetic neurons. The effect of surface charge on the apparent saturation of the channel with Ba2+ was examined by varying [Ba2+]o and ionic strength. The current increased with [Ba2+]o, and the I-V relation and the activation curve shifted to more positive voltages. The shift of activation could be described by Gouy-Chapman theory, with a surface charge density of 1 e- /140 A2, calculated from the Grahame equation. Changes in ionic strength (replacing N-methyl-D-glucamine with sucrose) shifted the activation curve as expected for a surface charge density of 1 e-/85 A2, in reasonable agreement with the value from changing [Ba2+]o. The instantaneous I-V for fully activated channels also changed with ionic strength, which could be described either by a low surface charge density (less than 1 e-/1,500 A2), or by block by NMG with Kd approximately 300 mM (assuming no surface charge). We conclude that the channel permeation mechanism sees much less surface charge than the gating mechanism. The peak inward current saturated with an apparent Kd = 11.6 mM for Ba2+, while the instantaneous I-V saturated with an apparent Kd = 23.5 mM at 0 mV. This discrepancy can be explained by a lower surface charge near the pore, compared to the voltage sensor. After correction for a surface charge near the pore of 1 e-/1,500 A2, the instantaneous I-V saturated as a function of local [Ba2+]o, with Kd = 65 mM. These results suggest that the channel pore does bind Ba2+ in a saturable manner, but the current-[Ba2+]o relationship may be significantly affected by surface charge.

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Selected References

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  1. Almers W., McCleskey E. W. Non-selective conductance in calcium channels of frog muscle: calcium selectivity in a single-file pore. J Physiol. 1984 Aug;353:585–608. doi: 10.1113/jphysiol.1984.sp015352. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Apell H. J., Bamberg E., Läuger P. Effects of surface charge on the conductance of the gramicidin channel. Biochim Biophys Acta. 1979 Apr 19;552(3):369–378. doi: 10.1016/0005-2736(79)90181-0. [DOI] [PubMed] [Google Scholar]
  3. Becchetti A., Arcangeli A., Del Bene M. R., Olivotto M., Wanke E. Intra and extracellular surface charges near Ca2+ channels in neurons and neuroblastoma cells. Biophys J. 1992 Oct;63(4):954–965. doi: 10.1016/S0006-3495(92)81665-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Begenisich T. 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. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Bell J. E., Miller C. Effects of phospholipid surface charge on ion conduction in the K+ channel of sarcoplasmic reticulum. Biophys J. 1984 Jan;45(1):279–287. doi: 10.1016/S0006-3495(84)84154-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Boland L. M., Morrill J. A., Bean B. P. omega-Conotoxin block of N-type calcium channels in frog and rat sympathetic neurons. J Neurosci. 1994 Aug;14(8):5011–5027. doi: 10.1523/JNEUROSCI.14-08-05011.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Byerly L., Chase P. B., Stimers J. R. Permeation and interaction of divalent cations in calcium channels of snail neurons. J Gen Physiol. 1985 Apr;85(4):491–518. doi: 10.1085/jgp.85.4.491. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Cai M., Jordan P. C. How does vestibule surface charge affect ion conduction and toxin binding in a sodium channel? Biophys J. 1990 Apr;57(4):883–891. doi: 10.1016/S0006-3495(90)82608-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Coronado R., Affolter H. Insulation of the conduction pathway of muscle transverse tubule calcium channels from the surface charge of bilayer phospholipid. J Gen Physiol. 1986 Jun;87(6):933–953. doi: 10.1085/jgp.87.6.933. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Cota G., Stefani E. Saturation of calcium channels and surface charge effects in skeletal muscle fibres of the frog. J Physiol. 1984 Jun;351:135–154. doi: 10.1113/jphysiol.1984.sp015238. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Cukierman S., Zinkand W. C., French R. J., Krueger B. K. Effects of membrane surface charge and calcium on the gating of rat brain sodium channels in planar bilayers. J Gen Physiol. 1988 Oct;92(4):431–447. doi: 10.1085/jgp.92.4.431. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Dani J. A. Ion-channel entrances influence permeation. Net charge, size, shape, and binding considerations. Biophys J. 1986 Mar;49(3):607–618. doi: 10.1016/S0006-3495(86)83688-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Elmslie K. S., Kammermeier P. J., Jones S. W. Reevaluation of Ca2+ channel types and their modulation in bullfrog sympathetic neurons. Neuron. 1994 Jul;13(1):217–228. doi: 10.1016/0896-6273(94)90471-5. [DOI] [PubMed] [Google Scholar]
  14. FRANKENHAEUSER B., HODGKIN A. L. The action of calcium on the electrical properties of squid axons. J Physiol. 1957 Jul 11;137(2):218–244. doi: 10.1113/jphysiol.1957.sp005808. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Ganitkevich VYa, Shuba M. F., Smirnov S. V. Saturation of calcium channels in single isolated smooth muscle cells of guinea-pig taenia caeci. J Physiol. 1988 May;399:419–436. doi: 10.1113/jphysiol.1988.sp017089. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Gilbert D. L., Ehrenstein G. Effect of divalent cations on potassium conductance of squid axons: determination of surface charge. Biophys J. 1969 Mar;9(3):447–463. doi: 10.1016/S0006-3495(69)86396-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Green W. N., Andersen O. S. Surface charges and ion channel function. Annu Rev Physiol. 1991;53:341–359. doi: 10.1146/annurev.ph.53.030191.002013. [DOI] [PubMed] [Google Scholar]
  18. Green W. N., Weiss L. B., Andersen O. S. Batrachotoxin-modified sodium channels in planar lipid bilayers. Ion permeation and block. J Gen Physiol. 1987 Jun;89(6):841–872. doi: 10.1085/jgp.89.6.841. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
  20. Hess P., Lansman J. B., Tsien R. W. Calcium channel selectivity for divalent and monovalent cations. Voltage and concentration dependence of single channel current in ventricular heart cells. J Gen Physiol. 1986 Sep;88(3):293–319. doi: 10.1085/jgp.88.3.293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Hess P., Tsien R. W. Mechanism of ion permeation through calcium channels. 1984 May 31-Jun 6Nature. 309(5967):453–456. doi: 10.1038/309453a0. [DOI] [PubMed] [Google Scholar]
  22. Hille B. Charges and potentials at the nerve surface. Divalent ions and pH. J Gen Physiol. 1968 Feb;51(2):221–236. doi: 10.1085/jgp.51.2.221. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Hille B., Woodhull A. M., Shapiro B. I. Negative surface charge near sodium channels of nerve: divalent ions, monovalent ions, and pH. Philos Trans R Soc Lond B Biol Sci. 1975 Jun 10;270(908):301–318. doi: 10.1098/rstb.1975.0011. [DOI] [PubMed] [Google Scholar]
  24. Ji S., Weiss J. N., Langer G. A. Modulation of voltage-dependent sodium and potassium currents by charged amphiphiles in cardiac ventricular myocytes. Effects via modification of surface potential. J Gen Physiol. 1993 Mar;101(3):355–375. doi: 10.1085/jgp.101.3.355. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Jones S. W., Marks T. N. Calcium currents in bullfrog sympathetic neurons. I. Activation kinetics and pharmacology. J Gen Physiol. 1989 Jul;94(1):151–167. doi: 10.1085/jgp.94.1.151. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Jones S. W. Sodium currents in dissociated bull-frog sympathetic neurones. J Physiol. 1987 Aug;389:605–627. doi: 10.1113/jphysiol.1987.sp016674. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Kass R. S., Krafte D. S. Negative surface charge density near heart calcium channels. Relevance to block by dihydropyridines. J Gen Physiol. 1987 Apr;89(4):629–644. doi: 10.1085/jgp.89.4.629. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Kuffler S. W., Sejnowski T. J. Peptidergic and muscarinic excitation at amphibian sympathetic synapses. J Physiol. 1983 Aug;341:257–278. doi: 10.1113/jphysiol.1983.sp014805. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Kuo C. C., Hess P. A functional view of the entrances of L-type Ca2+ channels: estimates of the size and surface potential at the pore mouths. Neuron. 1992 Sep;9(3):515–526. doi: 10.1016/0896-6273(92)90189-k. [DOI] [PubMed] [Google Scholar]
  30. Kuo C. C., Hess P. Characterization of the high-affinity Ca2+ binding sites in the L-type Ca2+ channel pore in rat phaeochromocytoma cells. J Physiol. 1993 Jul;466:657–682. [PMC free article] [PubMed] [Google Scholar]
  31. Latorre R., Miller C. Conduction and selectivity in potassium channels. J Membr Biol. 1983;71(1-2):11–30. doi: 10.1007/BF01870671. [DOI] [PubMed] [Google Scholar]
  32. MacKinnon R., Latorre R., Miller C. Role of surface electrostatics in the operation of a high-conductance Ca2+-activated K+ channel. Biochemistry. 1989 Oct 3;28(20):8092–8099. doi: 10.1021/bi00446a020. [DOI] [PubMed] [Google Scholar]
  33. MacKinnon R., Miller C. Functional modification of a Ca2+-activated K+ channel by trimethyloxonium. Biochemistry. 1989 Oct 3;28(20):8087–8092. doi: 10.1021/bi00446a019. [DOI] [PubMed] [Google Scholar]
  34. Moczydlowski E., Alvarez O., Vergara C., Latorre R. Effect of phospholipid surface charge on the conductance and gating of a Ca2+-activated K+ channel in planar lipid bilayers. J Membr Biol. 1985;83(3):273–282. doi: 10.1007/BF01868701. [DOI] [PubMed] [Google Scholar]
  35. Naranjo D., Latorre R., Cherbavaz D., McGill P., Schumaker M. F. A simple model for surface charge on ion channel proteins. Biophys J. 1994 Jan;66(1):59–70. doi: 10.1016/S0006-3495(94)80750-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Naranjo D., Latorre R. Ion conduction in substates of the batrachotoxin-modified Na+ channel from toad skeletal muscle. Biophys J. 1993 Apr;64(4):1038–1050. doi: 10.1016/S0006-3495(93)81469-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Ohmori H., Yoshii M. Surface potential reflected in both gating and permeation mechanisms of sodium and calcium channels of the tunicate egg cell membrane. J Physiol. 1977 May;267(2):429–463. doi: 10.1113/jphysiol.1977.sp011821. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Ravindran A., Kwiecinski H., Alvarez O., Eisenman G., Moczydlowski E. Modeling ion permeation through batrachotoxin-modified Na+ channels from rat skeletal muscle with a multi-ion pore. Biophys J. 1992 Feb;61(2):494–508. doi: 10.1016/S0006-3495(92)81854-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Rosenberg R. L., Hess P., Tsien R. W. Cardiac calcium channels in planar lipid bilayers. L-type channels and calcium-permeable channels open at negative membrane potentials. J Gen Physiol. 1988 Jul;92(1):27–54. doi: 10.1085/jgp.92.1.27. [DOI] [PMC free article] [PubMed] [Google Scholar]
  40. Smith P. A., Aschroft F. M., Fewtrell C. M. Permeation and gating properties of the L-type calcium channel in mouse pancreatic beta cells. J Gen Physiol. 1993 May;101(5):767–797. doi: 10.1085/jgp.101.5.767. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Werz M. A., Elmslie K. S., Jones S. W. Phosphorylation enhances inactivation of N-type calcium channel current in bullfrog sympathetic neurons. Pflugers Arch. 1993 Sep;424(5-6):538–545. doi: 10.1007/BF00374919. [DOI] [PubMed] [Google Scholar]
  42. Wilson D. L., Morimoto K., Tsuda Y., Brown A. M. Interaction between calcium ions and surface charge as it relates to calcium currents. J Membr Biol. 1983;72(1-2):117–130. doi: 10.1007/BF01870319. [DOI] [PubMed] [Google Scholar]
  43. Yue D. T., Marban E. Permeation in the dihydropyridine-sensitive calcium channel. Multi-ion occupancy but no anomalous mole-fraction effect between Ba2+ and Ca2+. J Gen Physiol. 1990 May;95(5):911–939. doi: 10.1085/jgp.95.5.911. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Zhu Y., Ikeda S. R. Anomalous permeation of Na+ through a putative K+ channel in rat superior cervical ganglion neurones. J Physiol. 1993 Aug;468:441–461. doi: 10.1113/jphysiol.1993.sp019781. [DOI] [PMC free article] [PubMed] [Google Scholar]

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