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Updated: Aug 10, 2026

High-throughput Screening for Small-molecule Modulators of Inward Rectifier Potassium Channels
Published on: January 27, 2013
[The blocking effects of extracellular Mn2+ on the inward rectifier potassium channel (IRK1)]
1Department of Physiology, Basic Science Institute, the Fourth Military Medical University, Xi'an 710032.
Aim And Methods:
Two-microelectrode voltage clamp (TEV) method was used to study the blocking effects of extracellular Mn2+ on the inward rectifier potassium channel (IRK1) expressed in the Xenopus oocytes.
Results:
Mn2+ can concentration-, time- and vol-tage dependently block IRK1 instantaneous currents (2 ms after voltage applied). Mn2+ has almost no effect on the gating property of IRK1. IRK1 can not permeate Mn2+ because reverse potential did not changed. External Mn2+ can inhibit IRK1 macroscopic currents more powerfully when external Mn2+ concentration is lower and external Mn2+ can increases standard chord conductance of IRK1.
Conclusion:
External Mn2+ works through surface potential mechanism. Ba2+ is considered as one fast open channel blocker of IRK1 and three exponential fitting results indicates that external Mn2+ can compete with Ba2+ in the same binding site in IRK1 when external Ba2+ concentration is 30 mumol/L. These mean two different mechanisms about external Mn2+ blocking exist.
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