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. 1990 Jan;420:73–109. doi: 10.1113/jphysiol.1990.sp017902

Ca2(+)-activated K+ current involvement in neuronal function revealed by in situ single-channel analysis in Helix neurones.

M Gola 1, C Ducreux 1, H Chagneux 1
PMCID: PMC1190039  PMID: 2109063

Abstract

1. The properties of single calcium-activated potassium channels (or C-channels) were studied in cell-attached patches using the patch-clamp technique. Experiments were performed on identified Ca2(+)-dependent U cells in juvenile specimens (1-2 months old) of Helix aspersa. 2. The criteria used to identify C-channels were based on comparison between macroscopic C-currents and currents reconstructed from unitary recordings. Both currents had a slow activation rate at large positive potentials which turned into fast activation after large Ca2+ entries. Both currents were blocked by intracellularly injected EGTA. 3. The unitary conductance in normal (5 mM) or reduced (0.5 mM) [K+]o ranged from 24 to 65 pS (mean +/- S.D., 48 +/- 13; n = 64). With 85-110 mM [K+]o, which is approximately equal to the internal [K+], the conductance was 64 pS and the reversal potential was approximately 0 mV. 4. C-channels in U cells were distributed in clusters of three to ten channels (mean 5.05 channels in seventy-five patches). Calcium channels were present in patches containing clustered C-channels. C-channels within clusters behaved independently. 5. With patch electrode containing 8 mM-calcium, C-channels opened transiently upon patch depolarization. Reopenings in quiescent depolarized patches were induced by whole-cell spikes triggered by current pulses applied to an intracellular electrode. Apparent inactivation of C-channels in depolarized patches was in fact due to a decrease in [Ca2+]i resulting from inactivation of Ca2+ channels. 6. Calcium-free saline solutions in the patch electrodes prevented C-channels from opening upon patch depolarization. Entry of calcium through the surrounding membrane induced delayed openings in the patch. Peak opening probability Po occurred 330 +/- 30 ms after a brief Ca2+ entry with a lag period of 50-80 ms. With patch electrodes filled with Ca2(+)-containing saline solutions and under conditions which maximized C-channel opening, peak Po was reached in 20-50 ms. The same value was observed for the whole-cell C-current. 7. The peak Po at a given patch potential and in response to a whole-cell spike was not altered by a previous long-lasting patch depolarization, or by producing several successive Ca2+ entries. Thus, C-channels did not appear to be inactivated by depolarization or increase in [Ca2+]i. 8. C-channels were found to be relatively highly voltage dependent, with an e-fold increase in Po per 14.9 mV increase in potential.(ABSTRACT TRUNCATED AT 400 WORDS)

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Selected References

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  1. Adams P. R., Constanti A., Brown D. A., Clark R. B. Intracellular Ca2+ activates a fast voltage-sensitive K+ current in vertebrate sympathetic neurones. Nature. 1982 Apr 22;296(5859):746–749. doi: 10.1038/296746a0. [DOI] [PubMed] [Google Scholar]
  2. Ahmed Z., Connor J. A. Calcium regulation by and buffer capacity of molluscan neurons during calcium transients. Cell Calcium. 1988 Apr;9(2):57–69. doi: 10.1016/0143-4160(88)90025-5. [DOI] [PubMed] [Google Scholar]
  3. Almers W., Stirling C. Distribution of transport proteins over animal cell membranes. J Membr Biol. 1984;77(3):169–186. doi: 10.1007/BF01870567. [DOI] [PubMed] [Google Scholar]
  4. Alvarez-Leefmans F. J., Rink T. J., Tsien R. Y. Free calcium ions in neurones of Helix aspersa measured with ion-selective micro-electrodes. J Physiol. 1981 Jun;315:531–548. doi: 10.1113/jphysiol.1981.sp013762. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Barrett J. N., Magleby K. L., Pallotta B. S. Properties of single calcium-activated potassium channels in cultured rat muscle. J Physiol. 1982 Oct;331:211–230. doi: 10.1113/jphysiol.1982.sp014370. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Belardetti F., Schacher S., Siegelbaum S. A. Action potentials, macroscopic and single channel currents recorded from growth cones of Aplysia neurones in culture. J Physiol. 1986 May;374:289–313. doi: 10.1113/jphysiol.1986.sp016080. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Chad J. E., Eckert R. Calcium domains associated with individual channels can account for anomalous voltage relations of CA-dependent responses. Biophys J. 1984 May;45(5):993–999. doi: 10.1016/S0006-3495(84)84244-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Colquhoun D., Hawkes A. G. On the stochastic properties of single ion channels. Proc R Soc Lond B Biol Sci. 1981 Mar 6;211(1183):205–235. doi: 10.1098/rspb.1981.0003. [DOI] [PubMed] [Google Scholar]
  9. Cook D. L., Ikeuchi M., Fujimoto W. Y. Lowering of pHi inhibits Ca2+-activated K+ channels in pancreatic B-cells. Nature. 1984 Sep 20;311(5983):269–271. doi: 10.1038/311269a0. [DOI] [PubMed] [Google Scholar]
  10. Cottrell G. A., Davies N. W., Green K. A. Multiple actions of a molluscan cardioexcitatory neuropeptide and related peptides on identified Helix neurones. J Physiol. 1984 Nov;356:315–333. doi: 10.1113/jphysiol.1984.sp015467. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Eckert R., Lux H. D. Calcium-dependent depression of a late outward current in snail neurons. Science. 1977 Jul 29;197(4302):472–475. doi: 10.1126/science.17921. [DOI] [PubMed] [Google Scholar]
  12. Ewald D. A., Williams A., Levitan I. B. Modulation of single Ca2+-dependent K+-channel activity by protein phosphorylation. Nature. 1985 Jun 6;315(6019):503–506. doi: 10.1038/315503a0. [DOI] [PubMed] [Google Scholar]
  13. Farley J., Rudy B. Multiple types of voltage-dependent Ca2+-activated K+ channels of large conductance in rat brain synaptosomal membranes. Biophys J. 1988 Jun;53(6):919–934. doi: 10.1016/S0006-3495(88)83173-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Franciolini F. Calcium and voltage dependence of single Ca2+-activated K+ channels from cultured hippocampal neurons of rat. Biochim Biophys Acta. 1988 Sep 1;943(3):419–427. doi: 10.1016/0005-2736(88)90373-2. [DOI] [PubMed] [Google Scholar]
  15. Gallin E. K. Calcium- and voltage-activated potassium channels in human macrophages. Biophys J. 1984 Dec;46(6):821–825. doi: 10.1016/S0006-3495(84)84080-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Glasbey C. A., Martin R. J. The distribution of numbers of open channels in multi-channel patches. J Neurosci Methods. 1988 Jul;24(3):283–287. doi: 10.1016/0165-0270(88)90174-4. [DOI] [PubMed] [Google Scholar]
  17. Gola M., Hussy N., Crest M., Ducreux C. Time course of Ca and Ca-dependent K currents during molluscan nerve cell action potentials. Neurosci Lett. 1986 Oct 20;70(3):354–359. doi: 10.1016/0304-3940(86)90578-1. [DOI] [PubMed] [Google Scholar]
  18. Gorman A. L., Thomas M. V. Potassium conductance and internal calcium accumulation in a molluscan neurone. J Physiol. 1980 Nov;308:287–313. doi: 10.1113/jphysiol.1980.sp013472. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Hartung K., Hermann A. Fluctuations of the Ca2+-activated K+ current in Aplysia neurones. Biochim Biophys Acta. 1987 Feb 12;897(1):201–205. doi: 10.1016/0005-2736(87)90329-4. [DOI] [PubMed] [Google Scholar]
  20. Hermann A., Erxleben C. Charybdotoxin selectively blocks small Ca-activated K channels in Aplysia neurons. J Gen Physiol. 1987 Jul;90(1):27–47. doi: 10.1085/jgp.90.1.27. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Hermann A., Gorman A. L. Effects of tetraethylammonium on potassium currents in a molluscan neurons. J Gen Physiol. 1981 Jul;78(1):87–110. doi: 10.1085/jgp.78.1.87. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Hermann A., Hartung K. Noise and relaxation measurements of the Ca2+ activated K+ current in Helix neurones. Pflugers Arch. 1982 May;393(3):254–261. doi: 10.1007/BF00584079. [DOI] [PubMed] [Google Scholar]
  23. Hermann A., Hartung K. Properties of a Ca2+ activated K+ conductance in Helix neurones investigated by intracellular Ca2+ ionophoresis. Pflugers Arch. 1982 May;393(3):248–253. doi: 10.1007/BF00584078. [DOI] [PubMed] [Google Scholar]
  24. Heyer C. B., Lux H. D. Control of the delayed outward potassium currents in bursting pace-maker neurones of the snail, Helix pomatia. J Physiol. 1976 Nov;262(2):349–382. doi: 10.1113/jphysiol.1976.sp011599. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Hofmeier G., Lux H. D. The time courses of intracellular free calcium and related electrical effects after injection of CaCl2 into neurons of the snail, Helix pomatia. Pflugers Arch. 1981 Sep;391(3):242–251. doi: 10.1007/BF00596178. [DOI] [PubMed] [Google Scholar]
  26. Johansen J., Yang J., Kleinhaus A. L. Voltage-clamp analysis of the ionic conductances in a leech neuron with a purely calcium-dependent action potential. J Neurophysiol. 1987 Dec;58(6):1468–1484. doi: 10.1152/jn.1987.58.6.1468. [DOI] [PubMed] [Google Scholar]
  27. Kazachenko V. N., Geletyuk V. I. The potential-dependent K+ channel in molluscan neurones is organized in a cluster of elementary channels. Biochim Biophys Acta. 1984 Jun 13;773(1):132–142. doi: 10.1016/0005-2736(84)90558-3. [DOI] [PubMed] [Google Scholar]
  28. Lancaster B., Nicoll R. A. Properties of two calcium-activated hyperpolarizations in rat hippocampal neurones. J Physiol. 1987 Aug;389:187–203. doi: 10.1113/jphysiol.1987.sp016653. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Lang D. G., Ritchie A. K. Large and small conductance calcium-activated potassium channels in the GH3 anterior pituitary cell line. Pflugers Arch. 1987 Dec;410(6):614–622. doi: 10.1007/BF00581321. [DOI] [PubMed] [Google Scholar]
  30. Latorre R., Coronado R., Vergara C. K+ channels gated by voltage and ions. Annu Rev Physiol. 1984;46:485–495. doi: 10.1146/annurev.ph.46.030184.002413. [DOI] [PubMed] [Google Scholar]
  31. Latorre R., Vergara C., Hidalgo C. Reconstitution in planar lipid bilayers of a Ca2+-dependent K+ channel from transverse tubule membranes isolated from rabbit skeletal muscle. Proc Natl Acad Sci U S A. 1982 Feb;79(3):805–809. doi: 10.1073/pnas.79.3.805. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Lux H. D., Hofmeier G. Activation characteristics of the calcium-dependent outward potassium current in Helix. Pflugers Arch. 1982 Jul;394(1):70–77. doi: 10.1007/BF01108310. [DOI] [PubMed] [Google Scholar]
  33. Lux H. D., Hofmeier G. Properties of a calcium- and voltage-activated potassium current in Helix pomatia neurons. Pflugers Arch. 1982 Jul;394(1):61–69. doi: 10.1007/BF01108309. [DOI] [PubMed] [Google Scholar]
  34. Lux H. D., Nagy K. Single channel Ca2+ currents in Helix pomatia neurons. Pflugers Arch. 1981 Sep;391(3):252–254. doi: 10.1007/BF00596179. [DOI] [PubMed] [Google Scholar]
  35. Lux H. D., Neher E., Marty A. Single channel activity associated with the calcium dependent outward current in Helix pomatia. Pflugers Arch. 1981 Mar;389(3):293–295. doi: 10.1007/BF00584792. [DOI] [PubMed] [Google Scholar]
  36. MacDermott A. B., Weight F. F. Action potential repolarization may involve a transient, Ca2+-sensitive outward current in a vertebrate neurone. Nature. 1982 Nov 11;300(5888):185–188. doi: 10.1038/300185a0. [DOI] [PubMed] [Google Scholar]
  37. Magleby K. L., Pallotta B. S. Calcium dependence of open and shut interval distributions from calcium-activated potassium channels in cultured rat muscle. J Physiol. 1983 Nov;344:585–604. doi: 10.1113/jphysiol.1983.sp014957. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Marty A. Ca-dependent K channels with large unitary conductance in chromaffin cell membranes. Nature. 1981 Jun 11;291(5815):497–500. doi: 10.1038/291497a0. [DOI] [PubMed] [Google Scholar]
  39. Meech R. W., Standen N. B. Potassium activation in Helix aspersa neurones under voltage clamp: a component mediated by calcium influx. J Physiol. 1975 Jul;249(2):211–239. doi: 10.1113/jphysiol.1975.sp011012. [DOI] [PMC free article] [PubMed] [Google Scholar]
  40. Meech R. W., Thomas R. C. Effect of measured calcium chloride injections on the membrane potential and internal pH of snail neurones. J Physiol. 1980 Jan;298:111–129. doi: 10.1113/jphysiol.1980.sp013070. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Moczydlowski E., Latorre R. Gating kinetics of Ca2+-activated K+ channels from rat muscle incorporated into planar lipid bilayers. Evidence for two voltage-dependent Ca2+ binding reactions. J Gen Physiol. 1983 Oct;82(4):511–542. doi: 10.1085/jgp.82.4.511. [DOI] [PMC free article] [PubMed] [Google Scholar]
  42. Moolenaar W. H., Spector I. The calcium current and the activation of a slow potassium conductance in voltage-clamped mouse neuroblastoma cells. J Physiol. 1979 Jul;292:307–323. doi: 10.1113/jphysiol.1979.sp012852. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Nasi E., Tillotson D. The rate of diffusion of Ca2+ and Ba2+ in a nerve cell body. Biophys J. 1985 May;47(5):735–738. doi: 10.1016/S0006-3495(85)83972-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Oberhauser A., Alvarez O., Latorre R. Activation by divalent cations of a Ca2+-activated K+ channel from skeletal muscle membrane. J Gen Physiol. 1988 Jul;92(1):67–86. doi: 10.1085/jgp.92.1.67. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Pallotta B. S., Hepler J. R., Oglesby S. A., Harden T. K. A comparison of calcium-activated potassium channel currents in cell-attached and excised patches. J Gen Physiol. 1987 Jun;89(6):985–997. doi: 10.1085/jgp.89.6.985. [DOI] [PMC free article] [PubMed] [Google Scholar]
  46. Partridge L. D., Swandulla D. Single Ca-activated cation channels in bursting neurons of Helix. Pflugers Arch. 1987 Dec;410(6):627–631. doi: 10.1007/BF00581323. [DOI] [PubMed] [Google Scholar]
  47. Pennefather P., Lancaster B., Adams P. R., Nicoll R. A. Two distinct Ca-dependent K currents in bullfrog sympathetic ganglion cells. Proc Natl Acad Sci U S A. 1985 May;82(9):3040–3044. doi: 10.1073/pnas.82.9.3040. [DOI] [PMC free article] [PubMed] [Google Scholar]
  48. Petersen O. H., Maruyama Y. Calcium-activated potassium channels and their role in secretion. Nature. 1984 Feb 23;307(5953):693–696. doi: 10.1038/307693a0. [DOI] [PubMed] [Google Scholar]
  49. Quandt F. N. Three kinetically distinct potassium channels in mouse neuroblastoma cells. J Physiol. 1988 Jan;395:401–418. doi: 10.1113/jphysiol.1988.sp016926. [DOI] [PMC free article] [PubMed] [Google Scholar]
  50. Ram J. L., Dagan D. Inactivating and non-inactivating outward current channels in cell-attached patches of Helix neurons. Brain Res. 1987 Mar 3;405(1):16–25. doi: 10.1016/0006-8993(87)90985-1. [DOI] [PubMed] [Google Scholar]
  51. Romey G., Lazdunski M. The coexistence in rat muscle cells of two distinct classes of Ca2+-dependent K+ channels with different pharmacological properties and different physiological functions. Biochem Biophys Res Commun. 1984 Jan 30;118(2):669–674. doi: 10.1016/0006-291x(84)91355-x. [DOI] [PubMed] [Google Scholar]
  52. Rudy B. Diversity and ubiquity of K channels. Neuroscience. 1988 Jun;25(3):729–749. doi: 10.1016/0306-4522(88)90033-4. [DOI] [PubMed] [Google Scholar]
  53. Schwarz W., Passow H. Ca2+-activated K+ channels in erythrocytes and excitable cells. Annu Rev Physiol. 1983;45:359–374. doi: 10.1146/annurev.ph.45.030183.002043. [DOI] [PubMed] [Google Scholar]
  54. Simon S. M., Llinás R. R. Compartmentalization of the submembrane calcium activity during calcium influx and its significance in transmitter release. Biophys J. 1985 Sep;48(3):485–498. doi: 10.1016/S0006-3495(85)83804-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Singer J. J., Walsh J. V., Jr Large-conductance Ca2+-activated K+ channels in freshly dissociated smooth muscle cells. Membr Biochem. 1986;6(2):83–110. doi: 10.3109/09687688609065445. [DOI] [PubMed] [Google Scholar]
  56. Smart T. G. Single calcium-activated potassium channels recorded from cultured rat sympathetic neurones. J Physiol. 1987 Aug;389:337–360. doi: 10.1113/jphysiol.1987.sp016660. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. Storm J. F. Intracellular injection of a Ca2+ chelator inhibits spike repolarization in hippocampal neurons. Brain Res. 1987 Dec 1;435(1-2):387–392. doi: 10.1016/0006-8993(87)91631-3. [DOI] [PubMed] [Google Scholar]
  58. Tanaka K., Minota S., Kuba K., Koyano K., Abe T. Differential effects of apamin on Ca2+-dependent K+ currents in bullfrog sympathetic ganglion cells. Neurosci Lett. 1986 Sep 12;69(3):233–238. doi: 10.1016/0304-3940(86)90485-4. [DOI] [PubMed] [Google Scholar]
  59. Taylor P. S. Selectivity and patch measurements of A-current channels in Helix aspersa neurones. J Physiol. 1987 Jul;388:437–447. doi: 10.1113/jphysiol.1987.sp016623. [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. Wong B. S., Lecar H., Adler M. Single calcium-dependent potassium channels in clonal anterior pituitary cells. Biophys J. 1982 Sep;39(3):313–317. doi: 10.1016/S0006-3495(82)84522-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  61. Woolum J. C., Gorman A. L. Time dependence of the calcium-activated potassium current. Biophys J. 1981 Oct;36(1):297–302. doi: 10.1016/S0006-3495(81)84729-7. [DOI] [PMC free article] [PubMed] [Google Scholar]

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