Advertisement

Blockage of Neuronal Low-Threshold Ca2+ Channels by Extracellular Mg2+

  • H. D. Lux
  • E. Carbone

Abstract

Mg2+ belongs to the category of abundant extracellular and intracellular cations and has biologically relevant chemical properties (for review see Flatman 1984). Mg2+ ions are small compared with other earth alkaline ions and have a large hydration shell. Water substitution in Mg2+ aquocomplexes by ligands is known to occur by 3–4 orders of magnitude slower than in Ca2+ aquocomplexes (Diebler et al. 1969). Specificity of the binding of a comparably small metal ion like Mg2+ demands that the ligand be more tightly bound than the water to be substituted. Thus, Mg2+ ions are expected to pass with difficulty through small, water-filled channels of the excitable membrane. On the other hand, if Mg2+ ions are to compete effectively with other cations for passage, a ligand is required that binds the Mg2+ ion sufficiently tightly. Channels that are specifically permeable to divalent cations appear to be interesting candidates for studying these assumptions.

Keywords

Tail Current Dorsal Root Ganglion Cell Negative Membrane Potential Water Substitution Helix Neuron 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Akaike N, Lee KS, Brown AM (1978) The calcium currents of Helix neuron. J Gen Physiol 71:509–532CrossRefPubMedGoogle Scholar
  2. Aimers W, McCleskey EW, Palade PT (1984) A non-selective cation conductance in frog muscle membrane blocked by micromolar external calcium ions. J Physiol (Lond) 353:565–583CrossRefGoogle Scholar
  3. Byerly L, Hagiwara S (1981) Calcium channel. Ann Rev Neurosci 4:69–125CrossRefPubMedGoogle Scholar
  4. Carbone E, Lux HD (1987 a) Kinetics and selectivity of a low voltage-activated calcium current in chick and rat sensory neurones. J Physiol (Lond) 386:547–570CrossRefGoogle Scholar
  5. Carbone E, Lux HD (1987 b) Single low voltage-activated calcium channels in chick and rat sensory neurones. J Physiol (Lond) 386:571–601CrossRefGoogle Scholar
  6. Carbone E, Lux HD (1987 c) External Ca2+ ions block unitary Na+ currents through Ca2+ channels of cultured chick sensory neurones by favouring prolonged closures. J Physiol (Lond) 382:124PGoogle Scholar
  7. Carbone E, Lux HD (1988) ω-Conotoxin blockade distinguishes Ca from Na permeable states in neuronal calcium channels. Pflügers Arch 413:14–22CrossRefPubMedGoogle Scholar
  8. Diebler H, Eigen M, Ilgenfritz G, Maas G, Winkler R (1969) Kinetics and mechanism of reactions of main group metal ions with biological carriers. Pure Appl Chem 20:93–115CrossRefGoogle Scholar
  9. Flatman PW (1984) Magnesium transport. J Membr Biol 80:1–14CrossRefPubMedGoogle Scholar
  10. Frankenhäuser B, Hodgkin AL (1957) The action of calcium on the electrical properties of squid axons. J Physiol (Lond) 137:218–244CrossRefGoogle Scholar
  11. Fukushima Y, Hagiwara S (1985) Currents carried by monovalent cations through calcium channels in mouse neoplastic B lymphocytes. J Physiol (Lond) 358:255–284CrossRefGoogle Scholar
  12. Hagiwara S, Takahashi K (1967) Surface density of calcium ions and calcium spikes in the barnacle muscle fiber membrane. J Gen Physiol 50:583–601CrossRefPubMedPubMedCentralGoogle Scholar
  13. Kostyuk PG, Krishtal OA (1977) Effects of calcium and calcium-chelating agents on the inward and outward current in the membrane of mollusc neurones. J Physiol (Lond) 270:569–580CrossRefGoogle Scholar
  14. Kostyuk PG, Mironov SL, Doroshenko PA (1982) Energy profile of the calcium channel in the membrane of mollusc neurons. J Membr Biol 70:181–189CrossRefGoogle Scholar
  15. Lansman JB, Hess P, Tsien RW (1986) Blockade of Ca current through single calcium channels by Cd2+, Mg2+, and Ca2+: Voltage and concentration dependence of calcium entry into the pore. J Gen Physiol (Paris) 88:321–347CrossRefGoogle Scholar
  16. Lux HD, Carbone E (1987) External Ca ions block Na-conducting Ca channel by promoting open to closed transitions. In: Ovchinnikov YA, Hucho E (eds) Receptors and ion channels. De Gruyter, New York, pp 149–155Google Scholar
  17. Lux HD, Carbone E, Zucker H (1989) Block of Na+ ion permeation and selectivity of Ca channels. Ann NY Acad Sci (USA) 560:94–102CrossRefGoogle Scholar
  18. Matsuda H (1986) Sodium conductance in calcium channels of guinea-pig ventricular cells induced by removal of external calcium ions. Pflügers Arch 407:465–475CrossRefPubMedGoogle Scholar
  19. McCleskey EW, Fox AP, Feldman DH, Cruz LJ, Olivera BM, Tsien RW, Yoshikami D (1987) ω-Conotoxin: direct and persistent blockade of specific types of calcium channels in neurons but not in muscle. Proc Natl Acad Sci USA 84:4327–4331CrossRefPubMedPubMedCentralGoogle Scholar
  20. Tsien RW, Hess P, McCleskey EW, Rosenberg RL (1987) Calcium channels: mechanisms of selectivity, permeation, and block. Annu Rev Biophys Chem 16:265–290CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1991

Authors and Affiliations

  • H. D. Lux
    • 1
  • E. Carbone
    • 2
  1. 1.Abteilung NeurophysiologieMax-Planck-Institut für PsychiatriePlaneggGermany
  2. 2.Dipartimento di Anatomia e Fisiologia UmanaTorinoItaly

Personalised recommendations