Hostname: page-component-848d4c4894-2pzkn Total loading time: 0 Render date: 2024-05-01T03:00:30.025Z Has data issue: false hasContentIssue false
  • English
  • Français

Effects of pH on a high conductance Ca-dependent chloride channel: a patch-clamp study in Ascaris suum

Published online by Cambridge University Press:  06 April 2009

A. P. Robertson  and
R. J. Martin
A. P. Robertson*
Affiliation:
Department of Preclinical Veterinary Sciences, R.(D.) S.V.S., Summerhall, University of Edinburgh, Edinburgh EH9 1QH
R. J. Martin
Affiliation:
Department of Preclinical Veterinary Sciences, R.(D.) S.V.S., Summerhall, University of Edinburgh, Edinburgh EH9 1QH
*
*Corresponding author. Tel: 0131 650 6094. E-mail: alanr@lab0.vet.ed.ac.uk.
Get access Rights & Permissions [Opens in a new window]

Summary

Plasma membrane vesicles prepared from the bag region of the somatic muscle cells of the parasitic nematode Ascaris suum contain high conductance, voltage sensitive, Ca-dependent chloride channels, suggested to be involved in the excretion of carboxylic acids produced by the anaerobic respiration of glucose (Valkanov, Martin & Dixon, 1994). The effect of altered pH on this channel was investigated using the patch-clamp technique and isolated inside-out membrane patches. Changes in pH had little effect on channel conductances and only a small effect on reversal potentials. Under control conditions (symmetrical pH 7·2) the channel had the highest probability of opening at ∼ — 35 mV (the resting membrane potential of the cell). At positive membrane potentials the probability of opening decreased. The Boltzmann equation was used to describe the relationship between membrane potential and probability of channel opening, and to calculate the effective gating charge. Reduction of external pH produced an increase in the probability of channel opening at hyper-polarized membrane potentials. An increase in internal pH caused a voltage-independent increase in the probability of channel opening and made the effective gating charge less negative. The effect of reducing internal pH was marked: the channel then opened most frequently at positive membrane potentials and the probability of opening at —35 mV was greatly reduced. The decrease in internal pH changed the polarity of the effective gating charge. A simple model was constructed to describe the effects of pH on channel gating.

Keywords

patch-clampAscaris suumCl− channelpHeffective gating charge
Type
Research Article
Information
Parasitology , Volume 113 , Issue 2 , August 1996 , pp. 191 - 198
Copyright
Copyright © Cambridge University Press 1996

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Bretag, A. H. (1987). Muscle chloride channels. Physiological Reviews 67, 618–714.CrossRefGoogle ScholarPubMed
Brading, A. F. & Caldwell, P. C. (1971). The resting membrane potential of somatic muscle cells of Ascaris lumbricoides. Journal of Physiology 27, 605–624.CrossRefGoogle Scholar
Caldwell, P. C. & Ellory, J. C. (1968). Ion movements in somatic muscle cells of Ascaris lumbricoides. Journal of Physiology 197, 75–76P.Google ScholarPubMed
Castillo, Del J., de Mellow, W. C. & Morales, T. (1964). Influence of some ions on the membrane potential of Ascaris muscle. Journal of General Physiology 48, 129–140.Google Scholar
Castillo, Del J., Rivera, A., Solorzano, S. & Serrato, J. (1989). Some aspects of the neuromuscular system of Ascaris. Quarterly Journal of Experimental Physiology 74, 1071–1087.CrossRefGoogle ScholarPubMed
Dixon, D. M., Valkanov, M. & Martin, R. J. (1993). A patch-clamp study of the ionic selectivity of the large conductance, Ca-activated chloride channel in muscle vesicles prepared from Ascaris suum. Journal of Membrane Biology 131, 143–149.CrossRefGoogle ScholarPubMed
Franciolini, F. & Petris, A. (1988). Chloride channels of biological membranes. Archives of Biochemistry and Biophysics 261, 97–102.CrossRefGoogle Scholar
Hanke, H. & Miller, C. (1983). Single chloride channels from Torpedo electroplax; activation by protons. Journal of General Physiology 82, 25–45.CrossRefGoogle ScholarPubMed
Hille, B. (1968). Charges and potentials at the nerve surface: Divalent ions and pH. Journal of General Physiology 51, 221–236.CrossRefGoogle ScholarPubMed
Hille, B. (1992). Ionic Channels of Excitable Membranes. 2nd Edn.Sinauer Associates, Sunderland, Mass.Google Scholar
Jarman, M. (1959). Electric activity in muscle cells of Ascaris muscle. Nature, London 184, 1244.CrossRefGoogle Scholar
Logothetis, D. E., Movahedi, S., Satler, C., Lindpainter, K., Nadal-Ginard, B. (1992). Incremental reductions of positive charge within the S4 region of a voltage-gated K+ channel result in corresponding decrease in gating charge. Neuron 8, 531–540.CrossRefGoogle ScholarPubMed
Martin, R. J. (1980). The effect of GABA on the input conductance and membrane potential of Ascaris muscle. British Journal of Pharmacology 71, 99–106.CrossRefGoogle ScholarPubMed
Papazian, D. M., Timpe, L. C., Jan, Y. N. & Jan, L. Y. (1991). Alteration of voltage-dependence of Shaker potassium channel by mutations in the S4 sequence. Nature, London 349, 305–310.CrossRefGoogle ScholarPubMed
Rao, G. S. J., Wariso, B. A., Cook, H. W. H. & Harris, B. G. (1987). Reaction of Ascaris suum phosphofructokinase with diethylpyrocarbonate. Journal of Biological Chemistry 262, 14068–14073.CrossRefGoogle ScholarPubMed
Saz, H. J. & Weil, A. (1962). Pathway of formation of α-methyl valerate by Ascaris lumbricoides. Journal of Biological Chemistry 237, 2053–2056.CrossRefGoogle Scholar
Stühmer, W., Conti, F., Suzuki, H., Wang, X., Noda, M., Yahagi, N., Kubo, H. & Numa, s. (1989). Structural parts involved in activation of the sodium channel. Nature, London 339, 597–603.CrossRefGoogle ScholarPubMed
Thorn, P. & Martin, R. J. (1987). A high-conductance calcium-dependent chloride channel in Ascaris suum muscle. Quarterly Journal of Experimental Physiology 72, 31–49.CrossRefGoogle ScholarPubMed
Valkanov, M., Martin, R. J. & Dixon, D. M. (1994). The Ca-activated chloride channel of Ascaris suum conducts volatile fatty acids produced by anaerobic respiration: a patch-clamp study. Journal of Membrane Biology 138, 133–141.CrossRefGoogle ScholarPubMed
Valkanov, M. & Martin, R. J. (1995). A Cl channel in Ascaris suum selectively conducts dicarboxylic anion products of glucose fermentation and suggests a role in removal of waste organic anions. Journal of Membrane Biology 148, 41–49.CrossRefGoogle ScholarPubMed
Zagotta, W. N. & Aldrich, R. W. (1990). Voltage-dependent gating of Shaker A-type channels in Drosophila muscle. Journal of General Physiology 95, 29–60.CrossRefGoogle ScholarPubMed