Conductance and selectivity properties of a substate of the rabbit sarcoplasmic reticulum channel.
In this paper I describe the occurrence and properties of a subconductance state of the cation-selective channel of the sarcoplasmic reticulum. The substate conductance is 60% of the major state conductance in every salt solution examined. When single channel conductance is plotted vs. ion concentration (for potassium or thallium salt solutions) the Michaelis-Menten constant is nearly the same for both conductance states, while the maximum conductance is reduced for the subconductance state. Both conductance states show anomalous conductance behavior in mixed potassium-thallium solutions that may be modeled in the same way. These results indicate that the ionic selectivity of the channel is the same for both open states.
Fox
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JA
D000818:Animals; D002412:Cations; D004553:Electric Conductivity; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D012996:Solutions; D013793:Thallium / Q000378:metabolism
D002412:Cations; D007473:Ion Channels; D012996:Solutions; D012964:Sodium; D013793:Thallium; D011188:Potassium