抄録
Using the ultramicroelectrode method developed by Ling and Gerard (1), Trautwein et al. (2) and Coraboeuf and Weidmann (3) have recorded slow diastolic depolarization from the pacemaker areas in isolated Purkinje fibers displaying spontaneous beats. Such electrical patterns of spontaneous activity have subsequently been recorded from all cardiac pacemakers studied by the intracellular microelectrode method. It is believed that the slow diastolic depolarization is responsible for the intrinsic rhythmicity of the sinus venosus of the frog heart (4-7), the sinus venosus of the turtle heart (8), the sinoatrial node of the rabbit heart (9), ectopic atrial pacemakers in the dog heart (10) and Purkinje fiber pacemakers from different mammals (2, 3, 11-14).
Observations on the effects of drugs on pacemaker areas of single cardiac muscle fibers would greatly contribute to the clarification of their action to a degree hitherto unattainable by conventional method, but until recently there have been very few reports regarding the effect of drugs on the intracellulary recorded membrane potentials of pacemaker areas. West et al. (9, 15) described the use of the ultramicroelectrode technique in localizing and recording from the sinoatrial node of the rabbit atria, and recorded the change in configuration of the pacemaker potentials as a result of rate modification either by acetylcholine or epinephrine.
The present report was designed to record the changes in configuration of the pacemaker potentials in the sinoatrial node of the isolated spontaneously beating rabbit atria after the application of a chelating agent, aconitine and antiarrhythmic agents.
