scholarly journals Single cardiac Purkinje cells: general electrophysiology and voltage-clamp analysis of the pace-maker current.

1984 ◽  
Vol 349 (1) ◽  
pp. 643-661 ◽  
Author(s):  
G Callewaert ◽  
E Carmeliet ◽  
J Vereecke
Keyword(s):  
Voltage Clamp ◽  
Purkinje Cells ◽  
Cardiac Purkinje Cells ◽  
Voltage Clamp Analysis ◽  
Pace Maker

Characteristics of L- and T-type Ca2+ currents in canine cardiac Purkinje cells

1989 ◽  
Vol 256 (5) ◽  
pp. H1478-H1492 ◽  
Author(s):  
Y. Hirano ◽  
H. A. Fozzard ◽  
C. T. January
Keyword(s):  
Kinetic Parameters ◽  
Voltage Clamp ◽  
Purkinje Cells ◽  
Current Density ◽  
Voltage Dependence ◽  
Cell Voltage ◽  
Voltage Clamp Technique ◽  
Recovery From Inactivation ◽  
Cardiac Purkinje Cells ◽  
Voltage Dependent

Two types of Ca2+ currents were recorded in single dialyzed canine cardiac Purkinje cells using a whole cell voltage clamp technique. T-type current was easily separated from L-type current, because its voltage dependence of inactivation and activation was more negative and it decayed rapidly. L-type current was available at more depolarized holding potentials, activated at more positive voltages, and decayed slowly. In 2 mM extracellular Ca2+ concentration [( Ca]o), the average peak T- and L-type current density was 1.70 and 2.87 pA/pF, respectively. T-type current was relatively insensitive to modification by Ca2+, nifedipine, Cd2+, BAY K 8644, or isoproterenol. T-type current was more sensitive to block by Ni2+ and amiloride. Replacement of Ca2+ by Ba2+ or Sr2+ did not increase T-type current. Changes in the Ca2+ or Ba2+ concentration caused parallel shifts in the voltage dependence of several kinetic parameters for L- and T-type current. In 2 mM [Ca]o, the V1/2 (Boltzmann fit) for inactivation of T-type current was -68 mV with a slope of 3.9, and for L-type current the V1/2 was -31 mV with a slope of 5.5. Recovery from inactivation of L- and T-type current was voltage dependent, and for similar conditions L-type current recovered from inactivation more rapidly than T-type current. These findings show that T- and L-type currents are large in cardiac Purkinje cells, and they can easily be separated by their voltage, kinetic, and pharmacological differences. Both may have important physiological roles.

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.

Voltage-clamp analysis of nodes of Ranvier in regenerated rat sciatic nerve

1987 ◽  
Vol 409 (2) ◽  
pp. 227-235 ◽  
Author(s):  
T. Brismar ◽  
C. Hildebrand ◽  
S. Berglund
Keyword(s):  
Sciatic Nerve ◽  
Voltage Clamp ◽  
Nodes Of Ranvier ◽  
Rat Sciatic Nerve ◽  
Voltage Clamp Analysis

Volumetric properties of intracellular compartments in canine cardiac Purkinje cells

1980 ◽  
Vol 238 (4) ◽  
pp. H561-H568
Author(s):  
S. R. Houser ◽  
A. R. Freeman
Keyword(s):  
Purkinje Cells ◽  
Regression Line ◽  
Resting Potential ◽  
Volumetric Properties ◽  
Bathing Medium ◽  
Cellular Volume ◽  
Cardiac Purkinje Fibers ◽  
Cardiac Purkinje Cells ◽  
Intracellular Compartments ◽  
The Relationship

Volumetric properties of canine cardiac Purkinje fibers were examined. Purkinje cells were superfused with anisosmolar solutions, and changes in extracellular space and relative cell volume were determined. The relationship between cellular volume and the osmolarity of the bathing medium was shown to be linear except in solutions of very low osmolarity. A linear regression line crossed the volume axis at 38%, suggesting an osmometric dead space of 38% and correspondingly an osmometric compartment comprising about 62% of the cell interior. To determine the volumetric properties of the "electrophysiological compartment," Purkinje cells were impaled with voltage-sensitive microelectrodes, and cellular resting potentials were recorded. When log K was plotted against resting potential (Em) in preparations bathed in normal and hyperosmotic solutions, it was shown that Em was increased in hyperosmotic solutions (13.5 and 21 mV in 600 and 850 mosM solutions, respectively). Calculations using the Nernst equation showed that the compartment containing the intracellular K involved in membrane electrical events behaves as a near-perfect osmometer in hyperosmotic solutions. Changes in the osmometric compartment were well correlated with K changes in the electrophysiological compartment, thus suggesting that the K is homogeneously distributed intracellularly.

Cardiac purkinje cells in culture

1984 ◽  
Vol 16 ◽  
pp. iv-iv
Author(s):  
E CANALE ◽  
J CAMPBELL ◽  
G CAMPBELL
Keyword(s):  
Purkinje Cells ◽  
Cells In Culture ◽  
Cardiac Purkinje Cells
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