The steady state TTX-sensitive (?window?) sodium current in cardiac Purkinje fibres

1979 ◽  
Vol 379 (2) ◽  
pp. 137-142 ◽  
Author(s):  
David Attwell ◽  
Ira Cohen ◽  
David Eisner ◽  
Mitsuyoshi Ohba ◽  
Carlos Ojeda
Keyword(s):  
Steady State ◽  
Sodium Current ◽  
Purkinje Fibres ◽  
Cardiac Purkinje Fibres

Tl+-Ions: Effects on the Automaticity of Sinoatrial Tissue and on dV/dtmax and iK2 of Cardiac Purkinje Fibres

1982 ◽  
Vol 37 (10) ◽  
pp. 1006-1014 ◽  
Author(s):  
C. chenbach ◽  
J. Wiemer ◽  
R. Ziskoven ◽  
U. Winter
Keyword(s):  
Guinea Pig ◽  
Cardiac Tissue ◽  
Sodium Current ◽  
Sinus Node ◽  
Beat Frequency ◽  
Contractile Force ◽  
Inactivation Kinetics ◽  
Purkinje Fibres ◽  
Thallium Poisoning ◽  
Cardiac Purkinje Fibres

The disrhythmic effects of thallium were investigated in various cardiac tissues to determine the primary site of intoxication with respect to ensuing arrhythmias. In isolated cardiac tissue Lameijer and van Zwieten [1] had contended that arrhythmias arise from the sinus node after thallium poisoning. To test this hypothesis we administered concentrations of Tl+ between 10"7 and 10-4 ᴍ to guinea pig sino-atrial preparations, to guinea pig papillary muscles and to sheep cardiac Purkinje fibres. In sino-artial preparations thallium provoked increases and decreases of spontaneous beat frequency which were not linked to corresponding changes in contractile force. In conductive tissue, Purkinje fibres, the inactivation kinetics of the fast sodium current and the pacemaker current iK2 were investigated by voltage clamp experiments. Here, thallium was seen to be essentially without toxic effects which could account for arrhythmias. In ventricular muscle actions potentials and contractile force were recorded simultaneously. Here again, ventricular arrhythmias are not to be expected from thallium intoxication in rather high concentrations. The findings support the view that arrhythmogenic effects of thallium are restricted to the sinus node.

Sign in / Sign up

Export Citation Format

Share Document