Ventricular Augmentor Fibers in the Cervical Vagosympathetic Trunk

The existence of ventricular augmentor fibers in the cervical vago-sympathetic trunk of the dog has been established by electrical stimulation after atropine. These fibers are distributed directly to both right and left ventricles, although preliminary evidence indicates disproportionate supply to the right ventricle. Augmentation in atrial systole during vagal stimulation after atropine also indicates significant innervation of atrial musculature, but these influences may often be subordinate to alterations in mean atrial pressure. Cardioaccel-erator responses may or may not accompany the augmentor changes in intraventricular pressure, and are usually more characteristic of right vagal stimulation.