Abstract
In order to clarify the functional connections between chemosensitive substrates in the ventral medullary surface and the nucleus retroambigualis (NRA), two sets of experiments were performed in 16 anesthetized, paralized and artificially ventilated cats.
Microstimulation in the intermediate area (IA) caused a decrease in the arterial blood pressure and the increment of phrenic nerve and inspiratory unit activity in the NRA: i. e. an increase in duration and number of inspiratory unitary discharge with a response latency of 3-10 msec by poststimulus time histogram. Stimulation in the NRA caused an increase in the arterial blood pressure, the phrenic nerve activity and the mean discharge frequency of chemosensitive unit in the IA with a response latency of 4-7 msec.
These experimental results show that microelectrical stimulation in the NRA or IA promote the neural respiratory output and further suggest that there are mutual facilitate connections between the two substrates through polysynaptic pathways and that the NRA may be involved in the central pathways consisting of neurons having chemosensitivity.
