COORDINATION OF THE CARDIAC-RELATED DISCHARGES OF SYMPATHETIC-NERVES WITH DIFFERENT TARGETS

Partial coherence analysis was used to remove the influences of pulse- synchronous baroreceptor nerve activity (as reflected by the arterial pulse) on the coherence of the cardiac-related discharges of sympathet ic nerve pairs in unanesthetized decerebrate cats. It can be predicted that the peak at the heart rate frequency in the ordinary coherence f unction relating the discharges of two nerves will be eliminated by ei ther partialization using the arterial pulse or surgical baroreceptor denervation, if the central circuits controlling the nerves share baro receptor inputs but are not interconnected. Contrary to this predictio n, in many experiments the peak was not eliminated by partialization u sing the arterial pulse. Moreover, partialization often nonuniformly r educed the peaks at the heart rate frequency in the coherence function s for different nerve pairs. These results are consistent with a model of multiple routes over which baroreceptor influences are distributed to the central circuits controlling different sympathetic nerves. Spe cifically, we propose that the direct route from the baroreceptors to each of the central circuits is complemented by cross talk among the c entral circuits.