ON THE TRANSMISSION OF EXCITATION IN THE ATRIAL MUSCLE DURING ACONITINEINDUCED FIBRILLATION

Abstract

1. Fibrillation was induced through the administration of aconitine on the right atrium isolated from a young rabbit, and the electrical activity was recorded simultaneously from two fibers of the fibrillating atrial muscle.
2. Synchronism in activities of two fibers in the fibrillating atrium decreased with increase in electrode distance. The decrease was evident in the transverse direction far more than in the longitudinal direction.
3. Two types of slow or small depolarizations in the fibrillating atrial muscle was discriminated. One was the oscillating slow potential in the ectopic pacemaker and the other was the “junctional potential” produced probably by the electrotonic spread of the action potential of the contiguous fiber through the intercellular junction.
4. Discussions were made on the behavior of the fibrillating atrial muscle, obtaining a conclusion that the fibrillation will be regulated by the degree of decrement of the safety factor in the intercellular junctional portions.