Studies on Cardiac parasympathetic Function Part 4. The Effect of Vagal Cardio-Accelerating Actions on the Action Potentials of the Bullfrog's Heart.

Abstract

1) Action potentials of atropinized bullfrog's heart are increased when the peripheral cut ends of vagus nerves are stimulated within the cranial cavity on a new “glycerine spot method” (Kotsuka,1952).
It is demonstrated electrophysiologically that there exist efferent cardioaccelarator fibers in a bullfrog's vagus nerves.
2) The height of action potentials of the normal bullfrog's heart is decreased when the peripheral cut ends of vagus nerves are stimulated within the cranial cavity on a new “glycerine spot method” It is evidenced electrophysiologically that the heart of bullfrogs is subjected to a “parasympathetic double efferent innervation”.
3) It is revealed electrophysiologically that there is no qualitative difference between efferent vagal cardio-accelerator effects and sympathetic cardio-accelerator effects of bullfrogs.