TY - JOUR

T1 - Characterisation of a cell swelling-activated K+-selective conductance of Ehrlich mouse ascites tumour cells

AU - Niemeyer, María Isabel

AU - Hougaard, Charlotte

AU - Hoffmann, Else Kay

AU - Jørgensen, Finn

AU - Stutzin, Andrés

AU - Sepúlveda, Francisco V.

PY - 2000

Y1 - 2000

N2 - 1.  The K+ and Cl- currents activated by hypotonic cell swelling were studied in Ehrlich ascites tumour cells using the whole-cell recording mode of the patch-clamp technique.2.  Currents were measured in the absence of added intracellular Ca2+ and with strong buffering of Ca2+. K+ current activated by cell swelling was measured as outward current at the Cl- equilibrium potential (ECl) under quasi-physiological gradients. It could be abolished by replacing extracellular Na+ with K+, thereby cancelling the driving force. Replacement with other cations suggested a selectivity sequence of K+ > Rb+ > NH4˜ Na+˜ Li+; Cs+ appeared to be inhibitory.3.  The current-voltage relationship of the volume-sensitive K+ current was well fitted with the Goldman-Hodgkin-Katz current equation between -130 and +20 mV with a permeability coefficient of around 10-6 cm s-1 with both physiological and high-K+ extracellular solutions.4.  The class III antiarrhythmic drug clofilium blocked the volume-sensitive K+ current in a voltage-independent manner with an IC50 of 32 µM. Clofilium was also found to be a strong inhibitor of the regulatory volume decrease response of Ehrlich cells.5.  Cell swelling-activated K+ currents of Ehrlich cells are voltage and calcium insensitive and are resistant to a range of K+ channel inhibitors. These characteristics are similar to those of the so-called background K+ channels.6.  Noise analysis of whole-cell current was consistent with a unitary conductance of 5.5 pS for the single channels underlying the K+ current evoked by cell swelling, measured at 0 mV under a quasi-physiological K+ gradient.

AB - 1.  The K+ and Cl- currents activated by hypotonic cell swelling were studied in Ehrlich ascites tumour cells using the whole-cell recording mode of the patch-clamp technique.2.  Currents were measured in the absence of added intracellular Ca2+ and with strong buffering of Ca2+. K+ current activated by cell swelling was measured as outward current at the Cl- equilibrium potential (ECl) under quasi-physiological gradients. It could be abolished by replacing extracellular Na+ with K+, thereby cancelling the driving force. Replacement with other cations suggested a selectivity sequence of K+ > Rb+ > NH4˜ Na+˜ Li+; Cs+ appeared to be inhibitory.3.  The current-voltage relationship of the volume-sensitive K+ current was well fitted with the Goldman-Hodgkin-Katz current equation between -130 and +20 mV with a permeability coefficient of around 10-6 cm s-1 with both physiological and high-K+ extracellular solutions.4.  The class III antiarrhythmic drug clofilium blocked the volume-sensitive K+ current in a voltage-independent manner with an IC50 of 32 µM. Clofilium was also found to be a strong inhibitor of the regulatory volume decrease response of Ehrlich cells.5.  Cell swelling-activated K+ currents of Ehrlich cells are voltage and calcium insensitive and are resistant to a range of K+ channel inhibitors. These characteristics are similar to those of the so-called background K+ channels.6.  Noise analysis of whole-cell current was consistent with a unitary conductance of 5.5 pS for the single channels underlying the K+ current evoked by cell swelling, measured at 0 mV under a quasi-physiological K+ gradient.

U2 - 10.1111/j.1469-7793.2000.00757.x

DO - 10.1111/j.1469-7793.2000.00757.x

M3 - Journal article

VL - 524

SP - 757

EP - 767

JO - The Journal of Physiology

JF - The Journal of Physiology

SN - 0022-3751

IS - 3

ER -