Cellular Electrical Uncoupling During Ischemia

1998 ◽  
pp. 195-216
Author(s):  
Michiel J. Janse ◽  
Hanno L. Tan ◽  
Lukas R. C. Dekker ◽  
André G. Kléber
Keyword(s):  
Electrical Uncoupling

Electrogastrography can recognize gastric electrical uncoupling in dogs

1997 ◽  
Vol 112 (6) ◽  
pp. 2006-2011 ◽  
Author(s):  
MP Mintchev ◽  
SJ Otto ◽  
KL Bowes
Keyword(s):  
Electrical Uncoupling ◽  
Gastric Electrical Uncoupling

Electrical properties of the gap junctional membrane studied in rat liver cell pairs

1988 ◽  
Vol 254 (2) ◽  
pp. C226-C234 ◽  
Author(s):  
E. C. Reverdin ◽  
R. Weingart
Keyword(s):  
Electrical Properties ◽  
Gap Junction ◽  
Rat Liver ◽  
Time Range ◽  
Voltage Gradient ◽  
Voltage Range ◽  
Cell Pair ◽  
Adult Rat ◽  
Electrical Uncoupling ◽  
Gap Junctional

Cell pairs isolated from adult rat liver were used to study the electrical properties of gap junctions. Each cell of a cell pair was connected to a suction pipette so as to enable whole cell tight-seal recording. A double voltage-clamp approach was adopted to control the voltage gradient across the gap junction and measure the transjunctional current. The current-voltage relationship of the gap junctional membrane was linear over the voltage range tested (+/- 50 m V). Under control conditions, the resistance of the gap junction, rj, was 15 M omega (n = 27; range, 4.6 to 45.8 M omega), corresponding to a conductance gj of 67 nS. rj was insensitive to the nonjunctional membrane potential, Vm (voltage range,-90 m V to + 40 m V). There was no indication of a time-dependent gating of rj (time range, 20 ms to 10 s). Dialysis with 1 mM CaCl2 produced irreversible electrical uncoupling without affecting the linearity of the relationship Vj/Ij.

R 56865 Delays Cellular Electrical Uncoupling in Ischemic Rabbit Papillary Muscle

1993 ◽  
Vol 25 (9) ◽  
pp. 1059-1066 ◽  
Author(s):  
Hanno L. Tan ◽  
Alexandra O. Netea ◽  
Mengalvio E. Sleeswijk ◽  
Pilar Mazón ◽  
Ruben Coronel ◽  
...  
Keyword(s):  
Papillary Muscle ◽  
Rabbit Papillary Muscle ◽  
Electrical Uncoupling ◽  
R 56865

Electrical uncoupling and impulse propagation in isolated sheep Purkinje fibers

1989 ◽  
Vol 257 (1) ◽  
pp. H179-H189 ◽  
Author(s):  
J. Jalife ◽  
S. Sicouri ◽  
M. Delmar ◽  
D. C. Michaels
Keyword(s):  
Action Potential ◽  
Electrical Coupling ◽  
Conduction Delay ◽  
Heart Cells ◽  
Hypertonic Solution ◽  
Purkinje Fibers ◽  
One Dimensional ◽  
Action Potential Propagation ◽  
Electrical Uncoupling ◽  
Impulse Propagation

Alterations in electrical coupling may have a major role in the development of cardiac rhythm and conduction disturbances. We have used microelectrodes and linear Purkinje fibers to analyze the relative importance of cell-to-cell coupling on action potential propagation and to study the changes in the relationship between conduction velocity (theta) and upstroke velocity (Vmax) induced by three agents (heptanol, hypertonic solution, and ouabain) known to alter gap junction resistance. Heptanol superfusion (1.5–3.0 mM) reversibly led to a major decrease in theta and ultimately to block at a time when Vmax had been reduced by approximately 38%. Conduction delay was closely correlated with an increase in intracellular resistance (Ri), calculated as the sum of myoplasmic and junctional resistances, assuming a one-dimensional cable model. Qualitatively similar results were obtained by superfusion with 0.1–0.5 mM ouabain or hypertonic Tyrode solution (up to 600 mM sucrose added) instead of heptanol. In contrast, when the Vmax vs. theta relationship was studied by changing the KCl from 4 to 20 mM, decreases in Vmax correlated well with changes in theta. No significant effects on Ri were observed during KCl superfusion. Finally, we developed a computer model of action potential propagation along a one-dimensional strand of 90 electrically coupled heart cells. By changing systematically the degree of electrical coupling or the maximum sodium conductance in the model and by studying the effects of these changes on propagation and Vmax, we obtained strong evidence supporting the validity of our experimental results. The overall data provide testable predictions regarding the role of electrical uncoupling on abnormal impulse propagation.

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