Open-channel subconductance state of K+ channel from cardiac sarcoplasmic reticulum

Joseph A Hill, R. Coronado, H. C. Strauss

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


We have characterized the K+ channel of canine cardiac sarcoplasmic reticulum in terms of its gating kinetics and conductance states. We demonstrate that the open channel dwells in two states, O1 and O2, where O1 is a true subconductance state of O2. The two open states are linked with a closed state by a cyclic gating scheme. Under certain circumstances, however, important information can be derived using a binary model. Each open state separately exhibited an ohmic current-voltage relation with unitary conductance values of 105 (O1) and 189 (O2) pS in 0.1 M K+. Gating between closed and open states was weakly voltage dependent, and we derive reaction rate constants for the state transitions. Finally, we postulate three models to explain the existence of a subconductance state (blockade, stenosis, flutter). We argue that a flutter model best accounts for our observations of O1.

Original languageEnglish (US)
Pages (from-to)H159-H164
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number1 27-1
StatePublished - 1990


  • Gating kinetics
  • Ion channel
  • Substate

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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