A Functional Study of the Nodose Ganglion of the Vagus with Degeneration Methods.

Abstract

In 11 adult cats, the vagus (5 on the left, 6 on the right) was cut at its exit from the jugular foramen above the nodose ganglion. In 5 experiments, the superior cervical sympathetic ganglion was also removed. Approximately 15 days' degeneration was allowed. The animals were anesthetized with urethane or ether, the carotid (in some cases the femoral) artery was cannulated and prepared for blood pressure tracings. In some experiments, movements of the thorax were also recorded as an index for the rate of respiration. The nerves were stimulated with rapid faradic stimuli delivered through platinum electrodes which were connected to a Harvard inductorium (approximately 2 amperes were delivered to the primary coil). Both the vagus and the cervical sympathetic trunk were sectioned and then stimulated distal to the section. The saphenous nerve was also stimulated in order to elicit pressor responses. With adequate stimuli (from 10 to 6 cm. coil separation), we have never seen any indication of the normal vagus inhibitory effect on the heart with slowing in rate and decrease in blood pressure. When the sympathetic trunk was stimulated 2 to 3 cm. below the superior cervical ganglion, no change in blood pressure was observed in 3 experiments with a coil separation of 6 cm. In the remaining experiments, a rise in blood pressure (1 to 7 mm.) was seen when the sympathetic trunk was stimulated in this position. The latent period was relatively long (2 to 3 sec.). The heart and respiratory rate changed but little and then with slight increases. This effect was present after removal of the superior cervical ganglion at the time of the original operation and thus was not due to descending conduction over axones arising in that ganglion.