Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1983 Apr;337:287–301. doi: 10.1113/jphysiol.1983.sp014624

Calcium-activated outward current in voltage-clamped hippocampal neurones of the guinea-pig.

D A Brown, W H Griffith
PMCID: PMC1199107  PMID: 6875931

Abstract

Slow clamp currents were recorded from CA1 and CA3 pyramidal neurones in slices of guinea-pig hippocampus maintained in vitro, using a single micro-electrode sample-and-hold technique. Depolarizing voltage commands evoked a time- and voltage-dependent outward current which was suppressed by removing external Ca or by adding Cd (0.5 mM) or Mn (5 mM). This Ca-dependent current (Ic) was not reduced by muscarinic agonists (unlike IM) but was greatly reduced by 5-20 mM-tetraethylammonium (TEA). Repolarizing IC tail currents reversed at -73 +/- 5 mV in 3 mM-K solution. The reversal potential became about 30 mV more positive on raising [K]o to 15 mM. No clear change in current amplitude or tail-current reversal potential occurred on adding Cs (2 mM), reducing [Cl]o from 128 to 10 mM, or replacing external Na with Tris. The underlying conductance GC was activated at membrane potentials positive to -45 mV. At -32 mV GC showed an approximately exponential increase with time, with a time constant of approximately 0.6 sec at 26 degrees C. Repolarizing tail currents declined exponentially with time, the time constant becoming shorter with increasing negative post-pulse potentials. When the clamp was switched off at the end of a depolarizing command of sufficient amplitude and duration to activate IC, a membrane hyperpolarization to -73 mV ensued, of similar amplitude and decay time to that following spontaneous action potentials. It is concluded that the clamp current observed in these experiments is probably the Ca-activated K current thought to contribute to the post-activation after-hyperpolarization in hippocampal neurones.

Full text

PDF
287

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  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. Alger B. E., Nicoll R. A. Epileptiform burst afterhyperolarization: calcium-dependent potassium potential in hippocampal CA1 pyramidal cells. Science. 1980 Dec 5;210(4474):1122–1124. doi: 10.1126/science.7444438. [DOI] [PubMed] [Google Scholar]
  3. Arnett D., Spraker T. E. Cross-correlation analysis of the maintained discharge of rabbit retinal ganglion cells. J Physiol. 1981 Aug;317:29–47. doi: 10.1113/jphysiol.1981.sp013812. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Barrett E. F., Barrett J. N., Crill W. E. Voltage-sensitive outward currents in cat motoneurones. J Physiol. 1980 Jul;304:251–276. doi: 10.1113/jphysiol.1980.sp013323. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Brown D. A., Adams P. R., Constanti A. Voltage-sensitive K-currents in sympathetic neurons and their modulation by neurotransmitters. J Auton Nerv Syst. 1982 Jul;6(1):23–35. doi: 10.1016/0165-1838(82)90019-4. [DOI] [PubMed] [Google Scholar]
  6. Brown D. A., Adams P. R. Muscarinic suppression of a novel voltage-sensitive K+ current in a vertebrate neurone. Nature. 1980 Feb 14;283(5748):673–676. doi: 10.1038/283673a0. [DOI] [PubMed] [Google Scholar]
  7. Brown D. A., Griffith W. H. Persistent slow inward calcium current in voltage-clamped hippocampal neurones of the guinea-pig. J Physiol. 1983 Apr;337:303–320. doi: 10.1113/jphysiol.1983.sp014625. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Constanti A., Brown D. A. M-Currents in voltage-clamped mammalian sympathetic neurones. Neurosci Lett. 1981 Jul 17;24(3):289–294. doi: 10.1016/0304-3940(81)90173-7. [DOI] [PubMed] [Google Scholar]
  9. Eckert R., Lux H. D. A voltage-sensitive persistent calcium conductance in neuronal somata of Helix. J Physiol. 1976 Jan;254(1):129–151. doi: 10.1113/jphysiol.1976.sp011225. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Godfraind J. M., Kawamura H., Krnjević K., Pumain R. Actions of dinitrophenol and some other metabolic inhibitors on cortical neurones. J Physiol. 1971 May;215(1):199–222. doi: 10.1113/jphysiol.1971.sp009465. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. 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]
  12. Hablitz J. J. Altered burst responses in hippocampal CA3 neurons injected with EGTA. Exp Brain Res. 1981;42(3-4):483–485. doi: 10.1007/BF00237513. [DOI] [PubMed] [Google Scholar]
  13. Hablitz J. J. Effects of intracellular injections of chloride and EGTA on postepileptiform-burst hyperpolarizations in hippocampal neurons. Neurosci Lett. 1981 Mar 10;22(2):159–163. doi: 10.1016/0304-3940(81)90080-x. [DOI] [PubMed] [Google Scholar]
  14. Halliwell J. V., Adams P. R. Voltage-clamp analysis of muscarinic excitation in hippocampal neurons. Brain Res. 1982 Oct 28;250(1):71–92. doi: 10.1016/0006-8993(82)90954-4. [DOI] [PubMed] [Google Scholar]
  15. Harvey J. A., Scholfield C. N., Brown D. A. Evoked surface-positive potentials in isolated mammalian olfactory cortex. Brain Res. 1974 Aug 16;76(2):235–245. doi: 10.1016/0006-8993(74)90457-0. [DOI] [PubMed] [Google Scholar]
  16. 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]
  17. Hotson J. R., Prince D. A. A calcium-activated hyperpolarization follows repetitive firing in hippocampal neurons. J Neurophysiol. 1980 Feb;43(2):409–419. doi: 10.1152/jn.1980.43.2.409. [DOI] [PubMed] [Google Scholar]
  18. Johnston D., Hablitz J. J., Wilson W. A. Voltage clamp discloses slow inward current in hippocampal burst-firing neurones. Nature. 1980 Jul 24;286(5771):391–393. doi: 10.1038/286391a0. [DOI] [PubMed] [Google Scholar]
  19. KANDEL E. R., SPENCER W. A. Electrophysiology of hippocampal neurons. II. After-potentials and repetitive firing. J Neurophysiol. 1961 May;24:243–259. doi: 10.1152/jn.1961.24.3.243. [DOI] [PubMed] [Google Scholar]
  20. Kostyuk P. G., Krishtal O. A. Effects of calcium and calcium-chelating agents on the inward and outward current in the membrane of mollusc neurones. J Physiol. 1977 Sep;270(3):569–580. doi: 10.1113/jphysiol.1977.sp011969. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Meech R. W. Calcium-dependent potassium activation in nervous tissues. Annu Rev Biophys Bioeng. 1978;7:1–18. doi: 10.1146/annurev.bb.07.060178.000245. [DOI] [PubMed] [Google Scholar]
  22. Nicoll R. A., Alger B. E. Synaptic excitation may activate a calcium-dependent potassium conductance in hippocampal pyramidal cells. Science. 1981 May 22;212(4497):957–959. doi: 10.1126/science.6262912. [DOI] [PubMed] [Google Scholar]
  23. Schwartzkroin P. A. Characteristics of CA1 neurons recorded intracellularly in the hippocampal in vitro slice preparation. Brain Res. 1975 Mar 7;85(3):423–436. doi: 10.1016/0006-8993(75)90817-3. [DOI] [PubMed] [Google Scholar]
  24. Schwartzkroin P. A., Pedley T. A. Slow depolarizing potentials in "epileptic" neurons. Epilepsia. 1979 Jun;20(3):267–277. doi: 10.1111/j.1528-1157.1979.tb04804.x. [DOI] [PubMed] [Google Scholar]
  25. Schwartzkroin P. A., Stafstrom C. E. Effects of EGTA on the calcium-activated afterhyperpolarization in hippocampal CA3 pyramidal cells. Science. 1980 Dec 5;210(4474):1125–1126. doi: 10.1126/science.6777871. [DOI] [PubMed] [Google Scholar]
  26. Thompson S. H. Three pharmacologically distinct potassium channels in molluscan neurones. J Physiol. 1977 Feb;265(2):465–488. doi: 10.1113/jphysiol.1977.sp011725. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Wilson W. A., Goldner M. M. Voltage clamping with a single microelectrode. J Neurobiol. 1975 Jul;6(4):411–422. doi: 10.1002/neu.480060406. [DOI] [PubMed] [Google Scholar]
  28. Wong R. K., Prince D. A. Afterpotential generation in hippocampal pyramidal cells. J Neurophysiol. 1981 Jan;45(1):86–97. doi: 10.1152/jn.1981.45.1.86. [DOI] [PubMed] [Google Scholar]
  29. Wong R. K., Prince D. A., Basbaum A. I. Intradendritic recordings from hippocampal neurons. Proc Natl Acad Sci U S A. 1979 Feb;76(2):986–990. doi: 10.1073/pnas.76.2.986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Wong R. K., Prince D. A. Participation of calcium spikes during intrinsic burst firing in hippocampal neurons. Brain Res. 1978 Dec 29;159(2):385–390. doi: 10.1016/0006-8993(78)90544-9. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES