Rostral dorsolateral pontine neurons with sympathetic nerve-related activity

Spike-triggered averaging, arterial pulse-triggered analysis, and coherence analysis were used to classify rostral dorsolateral pontine (RDLP) neurons into groups whose naturally occurring discharges were correlated to only t he 10-Hz rhythm (n = 29), to only the cardiac-related rhythm (n = 15), and to both rhythms (n = 15) in inferior cardiac sympathetic nerve discharge (S ND) of urethan-anesthetized cats. Most of the neurons with activity correla ted to only the cardiac-related rhythm were located medial to the other two groups of neurons. The firing rates of most RDLP neurons with activity cor related to only the 10-Hz rhythm (9 of 12) or both rhythms (7 of 8) were de creased during baroreceptor reflex-induced inhibition of SND produced by ao rtic obstruction; thus, they are presumed to be sympathoexcitatory. The fir ing rates of four of seven RDLP neurons with activity correlated to only th e cardiac-related rhythm increased during baroreceptor reflex activation; t hus, they may be sympathoinhibitory. We conclude that the RDLP contains a f unctionally heterogeneous population of neurons with sympathetic nerve-rela ted activity. These neurons could not be antidromically activated by stimul ation of the thoracic spinal cord.