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. 1983 Nov;44(2):281–284. doi: 10.1016/S0006-3495(83)84300-8

High intracellular pH reversibly prevents gating-charge immobilization in squid axons.

E Wanke, P L Testa, G Prestipino, E Carbone
PMCID: PMC1434832  PMID: 6652218

Abstract

Squid giant axons were used to study the reversible effects of high intracellular pH (pHi) on gating currents. Under depolarization, when Na channels are activated, internal solutions buffered at high pHi (10.2) affect considerably the time course of gating charge associated with channel closing, QOFF, with almost no alteration of QON records. In particular, at pHi 10.2 the charge corresponding to the fast phase of IgOFF, measured after long depolarizing pulses (7.7 ms), was consistently larger than that recorded at physiological pHi (7.2). This suggests that high pH prevents immobilization of gating charges induced by Na inactivation. In this respect, the present data agree reasonably well with previous observations, which show that pHi greater than 7.2 reversibly removes the fast Na inactivation with little effects on activation kinetics (Carbone, E., P. L. Testa, and E. Wanke, 1981, Biophys. J., 35:393-413; Brodwick, M.S., and D. C. Eaton, 1978, Science [Wash. DC], 200:1494-1496). Unexpectedly, high pH increases the amount of charge associated with the slow phase of IgOFF. In our opinion, this might be the result of either an increment of the net charge produced by the exposure to high pHi or that gating charges that return to the closed state might experience a larger fraction of the potential drop across the membrane (Neumcke, B., W. Schwarz, and R. Stampfli, 1980, Biophys. J., 31:325-332).

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Selected References

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

  1. 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]
  2. Armstrong C. M., Bezanilla F. Currents related to movement of the gating particles of the sodium channels. Nature. 1973 Apr 13;242(5398):459–461. doi: 10.1038/242459a0. [DOI] [PubMed] [Google Scholar]
  3. Armstrong C. M., Bezanilla F. Inactivation of the sodium channel. II. Gating current experiments. J Gen Physiol. 1977 Nov;70(5):567–590. doi: 10.1085/jgp.70.5.567. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Armstrong C. M., Gilly W. F. Fast and slow steps in the activation of sodium channels. J Gen Physiol. 1979 Dec;74(6):691–711. doi: 10.1085/jgp.74.6.691. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Bezanilla F., Armstrong C. M. Properties of the sodium channel gating current. Cold Spring Harb Symp Quant Biol. 1976;40:297–304. doi: 10.1101/sqb.1976.040.01.030. [DOI] [PubMed] [Google Scholar]
  6. Brodwick M. S., Eaton D. C. Sodium channel inactivation in squid axon is removed by high internal pH or tyrosine-specific reagents. Science. 1978 Jun 30;200(4349):1494–1496. doi: 10.1126/science.26973. [DOI] [PubMed] [Google Scholar]
  7. Carbone E. Removal of Na+ channels in squid giant axons by perfusion with trypsin. Biochim Biophys Acta. 1982 Dec 8;693(1):188–194. doi: 10.1016/0005-2736(82)90486-2. [DOI] [PubMed] [Google Scholar]
  8. Carbone E., Testa P. L., Wanke E. 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. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. HODGKIN A. L., HUXLEY A. F. A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol. 1952 Aug;117(4):500–544. doi: 10.1113/jphysiol.1952.sp004764. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Keynes R. D., Rojas E. Kinetics and steady-state properties of the charged system controlling sodium conductance in the squid giant axon. J Physiol. 1974 Jun;239(2):393–434. doi: 10.1113/jphysiol.1974.sp010575. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Khodorov B. I. Sodium inactivation and drug-induced immobilization of the gating charge in nerve membrane. Prog Biophys Mol Biol. 1981;37(2):49–89. doi: 10.1016/0079-6107(82)90020-7. [DOI] [PubMed] [Google Scholar]
  12. Neumcke B., Schwarz W., Stämpfli R. Increased charge displacement in the membrane of myelinated nerve at reduced extracellular pH. Biophys J. 1980 Sep;31(3):325–331. doi: 10.1016/S0006-3495(80)85062-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Nonner W. Effects of Leiurus scorpion venom on the "gating" current in myelinated nerve. Adv Cytopharmacol. 1979;3:345–352. [PubMed] [Google Scholar]
  14. Nonner W. Relations between the inactivation of sodium channels and the immobilization of gating charge in frog myelinated nerve. J Physiol. 1980 Feb;299:573–603. doi: 10.1113/jphysiol.1980.sp013143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Schauf C. L., Smith K. J. Gallamine triethiodide-induced modifications of sodium conductance in Myxicola giant axons. J Physiol. 1982 Feb;323:157–171. doi: 10.1113/jphysiol.1982.sp014066. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Swenson R. P., Jr Gating charge immobilization and sodium current inactivation in internally perfused crayfish axons. Nature. 1980 Oct 16;287(5783):644–645. doi: 10.1038/287644a0. [DOI] [PubMed] [Google Scholar]
  17. Wanke E., Carbone E., Testa P. L. K+ conductance modified by a titratable group accessible to protons from the intracellular side of the squid axon membrane. Biophys J. 1979 May;26(2):319–324. doi: 10.1016/S0006-3495(79)85251-0. [DOI] [PMC free article] [PubMed] [Google Scholar]

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