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


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 


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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

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