The kinetics of the inhibition by dihydroouabain of the sodium pump current in single rabbit cardiac Purkinje cells

1992 ◽  
Vol 345 (1) ◽  
Author(s):  
F.V. Bielen ◽  
H.G. Glitsch ◽  
F. Verdonck
Keyword(s):  
Purkinje Cells ◽  
Sodium Pump ◽  
Pump Current ◽  
Cardiac Purkinje Cells ◽  
Sodium Pump Current ◽  
Kinetics Of

Delayed K+ current and external K+ in single cardiac Purkinje cells

1989 ◽  
Vol 257 (6) ◽  
pp. C1086-C1092 ◽  
Author(s):  
F. Scamps ◽  
E. Carmeliet
Keyword(s):  
Voltage Clamp ◽  
Purkinje Cells ◽  
Cell Voltage ◽  
Inhibitory Effect ◽  
Free Solution ◽  
Cardiac Purkinje Cells ◽  
K Current ◽  
Kinetics Of ◽  
Direct Change ◽  
External K

The effect of external K+ on the delayed K+ current was investigated in rabbit single Purkinje cells. Whole cell voltage clamp and intracellular dialysis were used. At K+ concentrations less than 1 mM the kinetics of the delayed K+ current were not changed, but the conductance was markedly reduced. This effect was due to a direct change at an extracellular site and not due to secondary changes in intracellular Na+ or Ca2+ concentrations. A rise in intracellular Na+ or Ca2+ rather increased the delayed K+ current. The decrease in the delayed K+ current in low external K+ was absent when the experiments were done in Na+-free solution. It is concluded that external Na+ exerts an inhibitory effect on the conductance of the delayed K+ current.

Sodium-pump potentials and currents in guinea-pig ventricular muscles and myocytes

1999 ◽  
Vol 77 (5) ◽  
pp. 339-349 ◽  
Author(s):  
Yuji Kasamaki ◽  
An Chi Guo ◽  
Lesya M Shuba ◽  
Toshitsugu Ogura ◽  
Terence F McDonald
Keyword(s):  
Guinea Pig ◽  
Voltage Clamp ◽  
Cardiac Glycosides ◽  
Sodium Pump ◽  
Pump Current ◽  
Papillary Muscles ◽  
Maximal Concentration ◽  
Sodium Pump Current ◽  
Reproducible Manner

When guinea-pig papillary muscles were depolarized to ca. -30 mV by superfusion with K+-free Tyrode's solution supplemented with Ba2+, Ni2+, and D600, addition of Cs+ transiently hyperpolarized the membrane in a reproducible manner. The size of the hyperpolarization (pump potential) depended on the duration of the preceding K+-free exposure; peak amplitudes (Epmax) elicited by 10 mM Cs+ after 5-, 10-, and 15-min K+-free exposures were 12.9, 17.7, and 23.2 mV, respectively. Pump potentials were unaffected by external Cl- but suppressed by cardiac glycosides, hyperosmotic conditions, and low-Na+ solution. Using Epmax as an indicator of Na+ pump activation, the half-maximal concentration for activation by Cs+ was 12-16.3 mM. At 6 mM, Cs+ was three times less potent than Rb+ or K+ and five times more potent than Li+. From these findings, and correlative voltage-clamp data from myocytes, we calculate that (i) a pump current of 7.8 nA/cm2 generates an Epmax of 1 mV and (ii) resting pump current in normally polarized muscle (~0.16 µA/cm2) is five times smaller than previously estimated.Key words: sodium pump, cesium, rubidium, sodium pump current.

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