Superior Cervical Ganglionectomy Affects the Cardiorespiratory Network of the In Situ Arterially Perfused Brainstem Preparation

Abstract

Recently we found that the superior cervical ganglia projects to the nucleus tractus solitarii. Here, we report the effect of superior cervical ganglionectomy (SCGx) on cardiorespiratory activity in the in situ, arterially perfused brainstem preparation. For these studies, we used male Sprague‐Dawley rat pups (P25). Five days after either bilateral removal of superior cervical ganglia (n=14) or sham surgery (n=14), we recorded efferent activities of the phrenic nerve, cervical vagus nerve, and thoracic sympathetic chain and monitored heart rate and perfusion pressure. Baseline cardio‐respiratory patterns were recorded for 10 min to assess differences in patterning between the SCGx and sham groups. Then, we evoked the peripheral chemoreceptor reflex by injecting (intra‐arterially) sodium cyanide (100 μL of a 0.03% solution) and the baroreceptor reflex by increasing perfusion pressure (increasing the speed of the roller pump to its maximum). Baseline respiratory frequency was similar in the SCGx and sham group. However, the SCGx group had a greater but delayed response to chemoreceptor stimulation. Similarly, the SCGx group had a greater response to baroreceptor stimulation. Baseline heart rates (HR) were similar in both groups. For the SCGx group, HR decreased less than sham group during chemoreceptor stimulation; but, decreased more than the sham group during baroreceptor stimulation. Finally, the SCGx group required a greater perfusion pressure (PP) than the sham group during baseline; and had smaller increase in PP during chemoreceptor stimulation. These data indicate that superior cervical ganglia modulate vasomotor tone at rest and buffer cardio‐respiratory responses to chemoreceptor and baroreceptor reflexes.Support or Funding InformationNIH‐SPARC 1OT2OD023860‐02SJLewisThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.