Key result
Higher potassium solutions reduce the HERG channel water-ion coupling ratio by ~36%.
Why the study?
A quantitative measure of ion and water flux coupling ratio through ion channels is required to elucidate ion permeation mechanisms, but methods to measure this in HERG channels were lacking.
Population
HEK293 cells stably expressing the HERG potassium channel
Comparison
Exposure to hyperosmotic solutions for short periods (<1 s) vs baseline conditions
Design
Whole-cell patch-clamp with ultrafast solution switching (osmotic pulse method)
Authors
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Reveals K+-dependent HERG permeation modes; extends channel biophysics but leaves open clinical arrhythmia relevance.
An osmotic pulse method successfully measured the water-ion coupling ratio of the HERG potassium channel, revealing concentration-dependent changes in ion permeation modes.
Ando et al. (2005) studied this question. Osmotic pulse method (hyperosmotic solutions) was evaluated on Water-ion coupling ratio (n). Using an osmotic pulse method, the water-ion coupling ratio of the HERG potassium channel was 1.4 in 10 mM K+ solutions and decreased to 0.9 in 100 mM K+ solutions.
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