Key Points
- To characterize the potassium-selective currents activated by hypotonic cell swelling and evaluate their role in volume regulation in Ehrlich ascites tumour cells.
- Utilized the whole-cell recording mode of the patch-clamp technique under quasi-physiological ionic gradients in Ehrlich mouse ascites tumour cells.
- Buffered intracellular calcium strongly to isolate calcium-independent conductances during hypotonic shock.
- Assessed ion selectivity, current-voltage relationships using the Goldman-Hodgkin-Katz equation, pharmacological inhibition with clofilium, and unitary conductance via noise analysis.
- Swelling activated a potassium-selective current (selectivity: K+ > Rb+ > NH4+ ≈ Na+ ≈ Li+; inhibited by Cs+) that was insensitive to calcium and voltage, exhibiting a permeability coefficient of around 10^-6 cm s^-1.
- Clofilium blocked the swelling-induced potassium current in a voltage-independent manner with an IC50 of 32 μM and strongly inhibited the regulatory volume decrease response.
- Whole-cell current noise analysis indicated a unitary single-channel conductance of 5.5 pS at 0 mV.
Structured PICO
PPopulationEhrlich mouse ascites tumour cells
IInterventionHypotonic cell swelling and application of clofilium
OOutcomeCharacteristics of K+ and Cl- currents activated by hypotonic cell swellingsurrogate
Clofilium blocks volume-sensitive K+ currents in Ehrlich ascites tumour cells, which share characteristics with background K+ channels.