Pflügers Archiv

, Volume 422, Issue 3, pp 267–272 | Cite as

An early outward transient K+ current that depends on a preceding Na+ current and is enhanced by insulin

  • Kenneth Zierler
  • Fong -Sen Wu
Excitable Tissues and Central Nervous Physiology

Abstract

A whole-cell early transient outward current occurs in rat myoballs if and only if there is an immediatly preceding current of large amplitude through the voltage-gated, tetrodotoxin-inhibitable Na+ channel. This early outward transient is a K+ current, designated IK(Na+). Under the conditions in which IK(Na+) appears, simultaneous measurement of voltage and current, under voltage clamp, demonstrates that there is transient voltage escape to depolarized levels, peaking at about the time of peak inward Na+ current arid resembling an action potential. IK(Na+) was never seen in the absence of this breach of the voltage clamp, suggesting that IK(Na+) might be an artefact due to transient depolarization from the clamp. However, when the voltage escape was mimicked by voltage commands under conditions in which the Na+ channel was not activated, there was no IK(Na). Insulin increased or produced IK(Na+) even though insulin had no effect on INa or on the delayed rectifier K+ current or on the escape from voltage clamp. It is concluded that there is a population of rat myoballs in which there is an early outward K+ current that requires an immediately preceding current through the voltagegated tetrodotoxin-inhibitable Na+ channel and is enhanced by insulin.

Key words

Rat Myoball Potassium channel Potassium current Sodium current Insulin Voltage clamp 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Bader CR, Bernheim L, Bertrand D (1985) Sodium-activated potassium current in cultured avian neurons. Nature 317:540–542Google Scholar
  2. 2.
    Carmeliet E (1990) Na+ activated K+ channel in caridac myocytes: rectification, open probability and block. Biophysical J 57:118aGoogle Scholar
  3. 3.
    De Mello WC (1967) Effect of insulin on the membrane resistance of frog skeletal muscle. Life Sci 6:959–963Google Scholar
  4. 4.
    Dryer SE, Fujii JT, Martin AR (1989) A sodium-activated potassium current in cultivated brain stern neurons from chicks. J Physiol (Lond) 410:283–296Google Scholar
  5. 5.
    Egan TM, Dagan D, Levitan IB (1980) Calcium and sodium activate different channels in cultured rat olfactory bulb neurons. Biophysical J 557:313aGoogle Scholar
  6. 6.
    Haimann C, Bernheim L, Bertrand D, Bader CR (1990) Potassium current activated by intracellular sodium in quail trigeminal ganglion neurons. J Gen Physiol 95:951–979Google Scholar
  7. 7.
    Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflügers Arch 391:85–100Google Scholar
  8. 8.
    Hartung K (1985) Potentiation of a transient outward current by Na+ influx in crayfish neurons. Pflügers Arch 404:41–44Google Scholar
  9. 9.
    Wu F-S (1988) Effects of insulin on electrical activity of skeletal muscle. Dissertation for the PhD degree, The Johns Hopkins University, BaltimoreGoogle Scholar
  10. 10.
    Wu F-S, Rogus E, Zierler K (1989) Insulin depolarization of skeletal muscle in absence of external Na+. Diabetes 38:333–337Google Scholar
  11. 11.
    Wu F-S, Zierler K (1986) A Na+-conduction-dependent K+ channel in skeletal muscle. Fed Proc 45:1009Google Scholar
  12. 12.
    Wu F-S, Zierler K (1989) Calcium currents in rat myoballs and their inhibition by insulin. Endocrinology 125:2563–2572Google Scholar
  13. 13.
    Zierler K (1957) Increase in membrane potential of skeletal muscle produced by insulin. Science 126:1067Google Scholar
  14. 14.
    Zierler K (1960) Effect of insulin on potassium efflux from rat muscle in the presence and absence of glucose. Am J Physiol 198:1066–1070Google Scholar
  15. 15.
    Zierler K (1985) Membrane polarization and insulin action. In: Insulin, its Receptors, and Diabetes. Hollenberg M, ed. Marcel Dekker, New York, pp 141–179Google Scholar
  16. 16.
    Zierler K, Wu F-S (1986) Insulin promotes activation of a newly recognized K+ channel in skeletal muscle. Clin Res 34:727AGoogle Scholar
  17. 17.
    Zierler K, Wu F-S (1988) Insulin acts on Na, K and Ca currents. Trans Assoc Am Physicians 101:320–325Google Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • Kenneth Zierler
    • 1
  • Fong -Sen Wu
    • 1
  1. 1.Departments of Medicine and PhysiologyThe Johns Hopkins University School of MedicineBaltimoreUSA

Personalised recommendations