The class III antiarrhythmic agent E-4031 selectively blocks the inactivating inward-rectifying potassium current in rat anterior pituitary tumor cells (GH3/B6 cells).

TY - JOUR

T1 - The class III antiarrhythmic agent E-4031 selectively blocks the inactivating inward-rectifying potassium current in rat anterior pituitary tumor cells (GH3/B6 cells).

AU - Weinsberg, F

AU - Bauer, Christiane K.

AU - Schwarz, J R

PY - 1997

Y1 - 1997

N2 - Hyperpolarization-elicited potassium currents in GH3/B6 cells bathed in high-potassium external solution were recorded to assess effects of the class III antiarrhythmic agent E-4031 on the inactivating inward-rectifying potassium current (IK,IR). E-4031 potently blocked IK,IR with an IC50 value of 10 nM. The complete block of IK,IR achieved with concentrations >/= 1 microM revealed the presence of a non-inactivating outward-rectifying current which contributed to the membrane currents recorded under control conditions. The time dependence of the IK,IR block depended on the concentration of E-4031. Two other methanesulfonanilides were investigated: WAY-123,398 (10 microM) also totally blocked IK,IR, while sotalol (100 microM) was almost ineffective. Also lanthanum (100 microM) had only a very small effect on IK,IR. E-4031 did not affect sodium, calcium and voltage-dependent outward-rectifying potassium currents, suggesting a selective block of IK,IR in GH3/B6 cells. In an external solution containing 16 mM potassium, the E-4031-sensitive current was present as a steady outward current within a broad potential range positive to the potassium equilibrium potential, EK. In many, but not all, cells E-4031 induced an increase in the frequency of action potentials suggesting an important role of IK,IR in controlling cell excitability. Our experiments show that E-4031 is a valuable tool in characterizing IK,IR and its physiological function.

AB - Hyperpolarization-elicited potassium currents in GH3/B6 cells bathed in high-potassium external solution were recorded to assess effects of the class III antiarrhythmic agent E-4031 on the inactivating inward-rectifying potassium current (IK,IR). E-4031 potently blocked IK,IR with an IC50 value of 10 nM. The complete block of IK,IR achieved with concentrations >/= 1 microM revealed the presence of a non-inactivating outward-rectifying current which contributed to the membrane currents recorded under control conditions. The time dependence of the IK,IR block depended on the concentration of E-4031. Two other methanesulfonanilides were investigated: WAY-123,398 (10 microM) also totally blocked IK,IR, while sotalol (100 microM) was almost ineffective. Also lanthanum (100 microM) had only a very small effect on IK,IR. E-4031 did not affect sodium, calcium and voltage-dependent outward-rectifying potassium currents, suggesting a selective block of IK,IR in GH3/B6 cells. In an external solution containing 16 mM potassium, the E-4031-sensitive current was present as a steady outward current within a broad potential range positive to the potassium equilibrium potential, EK. In many, but not all, cells E-4031 induced an increase in the frequency of action potentials suggesting an important role of IK,IR in controlling cell excitability. Our experiments show that E-4031 is a valuable tool in characterizing IK,IR and its physiological function.

U2 - 10.1007/s004240050356

DO - 10.1007/s004240050356

M3 - SCORING: Zeitschriftenaufsatz

VL - 434

SP - 1

EP - 10

JO - PFLUG ARCH EUR J PHY

JF - PFLUG ARCH EUR J PHY

SN - 0031-6768

IS - 1

M1 - 1

ER -