Comparison of early afterdepolarization induced by cesium chloride in mouse atrial and ventricular fibers.
OBJECTIVE
To study the similarities and the differences in the induction of early afterdepolarization (EAD) by CsCl, a blocker of potassium channels, between mouse atrial and ventricular fibers.


METHODS
Papillary muscle from left ventricle or a small piece of right atrium of Swiss Albino mouse was isolated. Transmembrane action potential (AP) and EAD were recorded using the conventional microelectrode method.


RESULTS
CsCl induced EAD directly in the mouse atrial and ventricular fibers on the basis of elongation of action potential duration (APD). In both preparations EAD appeared after 5-15 min exposure to CsCl and the take-off potentials (TOP) were in the same range (-30 to -60 mV). But the inducing concentration in ventricular fibers (3 mmol.L-1) was lower than that in atrial fibers (5 mmol.L-1), and most of the EAD induced in atrium belonged to the triggered burst type (6/9) which demonstrated the property of cycle length (CL)-dependence while the EAD occurred in ventricle mainly belonged to the second plateau type (14/17) which showed no definite relation with the CL.


CONCLUSIONS
Low concentration of CsCl induced EAD more easily in mouse ventricular fibers than in atrial fibers, and the types of EAD were also different from each other. These suggested that there might be some differences in potassium channels between mouse atrial and ventricular fibers.
Zhou
Y Y
YY
Laboratory of Biological Membrane and Membrane Engineering, College of Life Science, Peking University, Beijing, China.
Liu
T F
TF
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D016275:Atrial Function; D002586:Cesium / Q000494:pharmacology*; D002712:Chlorides / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D026902:Potassium Channel Blockers; D016276:Ventricular Function
D002712:Chlorides; D026902:Potassium Channel Blockers; D002586:Cesium; C028019:cesium chloride