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. 1983 Dec;345:549–565. doi: 10.1113/jphysiol.1983.sp014996

Inactivation of calcium conductance characterized by tail current measurements in neurones of Aplysia californica.

R Eckert, D Ewald
PMCID: PMC1193815  PMID: 6420549

Abstract

Calcium tail currents, recorded at -40 mV after repolarization from 7 or 10 ms voltage-clamp depolarizations in axotomized Aplysia neurones in the presence of tetrodotoxin and tetraethylammonium, were used to investigate the inactivation of the calcium conductance without interference from contaminating potassium currents. Prior depolarization with a prepulse (V1) resulted in a reduction in size of the tail currents recorded following the test pulse (V2). The reduction occurred in both the fast (tau 1 less than 0.4 ms) and slow (tau 2 approximately equal to 2.0 ms) components of the tail current. The degree of inactivation remained constant when tail currents were measured at potentials ranging up to 30 mV on either side of the potassium equilibrium potential. Thus, any changes in potassium current must have contributed virtually nothing to the changes in tail current amplitude seen following presentation of the prepulse. Inactivation was greatest following prepulses to potentials (+10 to +40 mV) that produce maximal entry of calcium ions, and declined to about zero as the prepulse approached the calcium equilibrium potential. For V1 potentials above +50 mV, the prepulse caused an apparent short-term facilitation of V2 tail currents in EGTA-injected neurones. This effect, detected up to 50 ms following the pulse, is of uncertain origin. Pressure injection of calcium ions caused reduction in the size of the tail current, which was restored by subsequent injection of EGTA. Tail current amplitude was reduced by presentation of the prepulse for all test pulse voltages, but the measured inactivation declined exponentially towards a minimum with test pulses of increasingly positive potential. Removal of inactivation following a 200 ms prepulse was greatly accelerated by injection of EGTA. The EGTA-resistant inactivation remaining at short times decayed with a time constant of about 0.12 s. The relation of tail current reduction to prepulse voltage is consistent with the interpretation that the EGTA-resistant inactivation remaining at short times depends on entry of calcium ions during the prepulse, as does the EGTA-sensitive inactivation remaining at later times. It is proposed that the 'EGTA-resistant' phase of inactivation results from loading of EGTA with calcium ions near the inner surface of the membrane during sustained calcium entry, allowing the intracellular calcium concentration to rise. The results provide further evidence for a calcium-mediated inactivation of the calcium conductance.(ABSTRACT TRUNCATED AT 400 WORDS)

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Selected References

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  1. Adams D. J., Gage P. W. Characteristics of sodium and calcium conductance changes produced by membrane depolarization in an Aplysia neurone. J Physiol. 1979 Apr;289:143–161. doi: 10.1113/jphysiol.1979.sp012729. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Akaike N., Lee K. S., Brown A. M. The calcium current of Helix neuron. J Gen Physiol. 1978 May;71(5):509–531. doi: 10.1085/jgp.71.5.509. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Almers W., Palade P. T. Slow calcium and potassium currents across frog muscle membrane: measurements with a vaseline-gap technique. J Physiol. 1981 Mar;312:159–176. doi: 10.1113/jphysiol.1981.sp013622. [DOI] [PMC free article] [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. Armstrong C. M., Bezanilla F. Charge movement associated with the opening and closing of the activation gates of the Na channels. J Gen Physiol. 1974 May;63(5):533–552. doi: 10.1085/jgp.63.5.533. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Ashcroft F. M., Stanfield P. R. Calcium dependence of the inactivation of calcium currents in skeletal muscle fibers of an insect. Science. 1981 Jul 10;213(4504):224–226. doi: 10.1126/science.213.4504.224. [DOI] [PubMed] [Google Scholar]
  7. Brehm P., Eckert R. Calcium entry leads to inactivation of calcium channel in Paramecium. Science. 1978 Dec 15;202(4373):1203–1206. doi: 10.1126/science.103199. [DOI] [PubMed] [Google Scholar]
  8. Brehm P., Eckert R., Tillotson D. Calcium-mediated inactivation of calcium current in Paramecium. J Physiol. 1980 Sep;306:193–203. doi: 10.1113/jphysiol.1980.sp013391. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Brown A. M., Morimoto K., Tsuda Y., wilson D. L. Calcium current-dependent and voltage-dependent inactivation of calcium channels in Helix aspersa. J Physiol. 1981 Nov;320:193–218. doi: 10.1113/jphysiol.1981.sp013944. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Byerly L., Hagiwara S. Calcium currents in internally perfused nerve cell bodies of Limnea stagnalis. J Physiol. 1982 Jan;322:503–528. doi: 10.1113/jphysiol.1982.sp014052. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Connor J. A., Stevens C. F. Voltage clamp studies of a transient outward membrane current in gastropod neural somata. J Physiol. 1971 Feb;213(1):21–30. doi: 10.1113/jphysiol.1971.sp009365. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Doroshenko P. A., Tsyndrenko A. Ia. Deistvie vnutrikletochnogo kal'tsiia na kal'tsievyi vkhodiashchii tok. Neirofiziologiia. 1978;10(2):203–205. [PubMed] [Google Scholar]
  13. Eckert R., Ewald D. Calcium tail currents in voltage-clamped intact nerve cell bodies of Aplysia californica. J Physiol. 1983 Dec;345:533–548. doi: 10.1113/jphysiol.1983.sp014995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Eckert R., Ewald D. Residual calcium ions depress activation of calcium-dependent current. Science. 1982 May 14;216(4547):730–733. doi: 10.1126/science.6281880. [DOI] [PubMed] [Google Scholar]
  15. 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]
  16. Eckert R., Tillotson D. L., Brehm P. Calcium-mediated control of Ca and K currents. Fed Proc. 1981 Jun;40(8):2226–2232. [PubMed] [Google Scholar]
  17. Eckert R., Tillotson D. L. Calcium-mediated inactivation of the calcium conductance in caesium-loaded giant neurones of Aplysia californica. J Physiol. 1981 May;314:265–280. doi: 10.1113/jphysiol.1981.sp013706. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Eckert R., Tillotson D. Potassium activation associated with intraneuronal free calcium. Science. 1978 Apr 28;200(4340):437–439. doi: 10.1126/science.644308. [DOI] [PubMed] [Google Scholar]
  19. Fenwick E. M., Marty A., Neher E. Sodium and calcium channels in bovine chromaffin cells. J Physiol. 1982 Oct;331:599–635. doi: 10.1113/jphysiol.1982.sp014394. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Gorman A. L., Hermann A. Internal effects of divalent cations on potassium permeability in molluscan neurones. J Physiol. 1979 Nov;296:393–410. doi: 10.1113/jphysiol.1979.sp013012. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Gorman A. L., Thomas M. V. Intracellular calcium accumulation during depolarization in a molluscan neurone. J Physiol. 1980 Nov;308:259–285. doi: 10.1113/jphysiol.1980.sp013471. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. HAGIWARA S., SAITO N. Voltage-current relations in nerve cell membrane of Onchidium verruculatum. J Physiol. 1959 Oct;148:161–179. doi: 10.1113/jphysiol.1959.sp006279. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. HODGKIN A. L., HUXLEY A. F. The dual effect of membrane potential on sodium conductance in the giant axon of Loligo. J Physiol. 1952 Apr;116(4):497–506. doi: 10.1113/jphysiol.1952.sp004719. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Hermann A., Gorman A. L. Effects of 4-aminopyridine on potassium currents in a molluscan neuron. J Gen Physiol. 1981 Jul;78(1):63–86. doi: 10.1085/jgp.78.1.63. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Kostyuk P. G., Krishtal O. A., Shakhovalov Y. A. Separation of sodium and calcium currents in the somatic membrane of mollusc neurones. J Physiol. 1977 Sep;270(3):545–568. doi: 10.1113/jphysiol.1977.sp011968. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. 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]
  27. 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]
  28. 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]
  29. Neher E. Two fast transient current components during voltage clamp on snail neurons. J Gen Physiol. 1971 Jul;58(1):36–53. doi: 10.1085/jgp.58.1.36. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Plant T. D., Standen N. B. Calcium current inactivation in identified neurones of Helix aspersa. J Physiol. 1981 Dec;321:273–285. doi: 10.1113/jphysiol.1981.sp013983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Standen N. B. Ca channel inactivation by intracellular Ca injection into Helix neurones. Nature. 1981 Sep 10;293(5828):158–159. doi: 10.1038/293158a0. [DOI] [PubMed] [Google Scholar]
  32. Standen N. B., Stanfield P. R. A binding-site model for calcium channel inactivation that depends on calcium entry. Proc R Soc Lond B Biol Sci. 1982 Dec 22;217(1206):101–110. doi: 10.1098/rspb.1982.0097. [DOI] [PubMed] [Google Scholar]
  33. Tillotson D. Inactivation of Ca conductance dependent on entry of Ca ions in molluscan neurons. Proc Natl Acad Sci U S A. 1979 Mar;76(3):1497–1500. doi: 10.1073/pnas.76.3.1497. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Zucker R. S. Tetraethylammonium contains an impurity which alkalizes cytoplasm and reduce calcium buffering in neurons. Brain Res. 1981 Mar 16;208(2):473–478. doi: 10.1016/0006-8993(81)90580-1. [DOI] [PubMed] [Google Scholar]

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