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Na channels in skeletal muscle concentrated near the neuromuscular junction

Abstract

Neuronal function depends crucially on the spatial segregation of specific membrane proteins, particularly the segregation associated with sites of synaptic contact. Understanding the factors governing this localization of proteins is a major goal of cellular neurobiology. A conspicuous example of synaptic specialization is the almost exclusive localization of vertebrate skeletal muscle acetylcholine (ACh) receptors to the subsynaptic membrane of the neuromuscular junction (for example, refs 1,2). The localization of other membrane proteins in skeletal muscle has been much less studied, but a knowledge of their distribution is crucial for understanding the factors governing regional specialization. We have explored the distribution in muscle of the voltage-gated Na channel responsible for the action potential using the loose patch-clamp technique3–5, and have measured Na currents in 5–10 µm-diameter membrane patches as a function of distance from the end plate region of snake and rat muscle fibres. Here we report that the Na current density immediately adjacent to the endplate is 5–10-fold higher than at regions away from the endplate. The increased Na current density falls off rapidly with distance, reaching the background level 100–200 µm from the endplate. Although one might expect ACh receptors to be concentrated near the region of ACh release, such a concentration for Na channels, which propagate the impulse throughout the length of the cell, is surprising and suggests that factors similar to those responsible for concentrating ACh receptors at the endplate also operate to concentrate Na channels.

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References

  1. Bekoff, A. & Betz, W. J. J. Physiol., Lond., 271, 25–40 (1977).

    Article  CAS  Google Scholar 

  2. Kuffler, S. W. & Yoshikami, D. J. Physiol., Lond. 244, 703–730 (1975).

    Article  CAS  Google Scholar 

  3. Stühmer, W. & Almers, W. Proc. natn. Acad. Sci. U.S.A. 79, 946–950 (1982).

    Article  ADS  Google Scholar 

  4. Stühmer, W., Roberts, W. M. & Aimers, W. in Single-channel Recording (eds Sakmann, & Neher, E. (Plenum, New York, 1983).

    Google Scholar 

  5. Almers, W., Stanfield, P. R. & Stühmer, W. J. Physiol., Lond. 336, 261–284 (1983).

    Article  CAS  Google Scholar 

  6. Salpeter, M. M. & Eldefrawi, M. E. J. Histochem. Cytochem. 21, 769–778 (1973).

    Article  CAS  Google Scholar 

  7. Almers, W., Roberts, W. M. & Ruff, R. L. J. Physiol., Lond. 347, 751–768 (1984).

    Article  CAS  Google Scholar 

  8. Nasledov, G. A., Volkov, E. M. & Poletaev, G. I. Experientia 38, 576–577 (1982).

    Article  CAS  Google Scholar 

  9. Thesleff, L., Vyskocil, F. & Ward, M. R. Acta physiol. Scand. 91, 196–202 (1974).

    Article  CAS  Google Scholar 

  10. Nastuk, W. L. & Alexander, J. T. Fedn Proc. 32, 333 (1973).

    Google Scholar 

  11. Betz, W. J., Caldwell, J. H. & Kinnamon, S. C. J. Physiol., Lond. 352, 189–202 (1984).

    Article  CAS  Google Scholar 

  12. Jaffe, L. F. & Nuccitelli, R. J. Cell Biol. 63, 614–628 (1974).

    Article  CAS  Google Scholar 

  13. Betz, W. J. & Caldwell, J. H. J. gen. Physiol. 83, 143–156 (1984).

    Article  CAS  Google Scholar 

  14. Katz, B. & Miledi, R. Proc. R. Soc. B216, 497–507 (1982).

    ADS  CAS  Google Scholar 

  15. Betz, W. J., Caldwell, J. H. & Kinnamon, S. C. J. gen. Physiol. 83, 175–192 (1984).

    Article  CAS  Google Scholar 

Download references

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Beam, K., Caldwell, J. & Campbell, D. Na channels in skeletal muscle concentrated near the neuromuscular junction. Nature 313, 588–590 (1985). https://doi.org/10.1038/313588a0

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