Electrophysiological investigation of sympathetic cardiac afferent fibers.

Abstract

SummaryCardiac sympathetic afferent activity was electrically evoked from several close cardiac nerves and recorded from the left T3 white ramus and sympathetic chain below T3 in anesthetized dogs. Electrical stimulation of sympathetic afferent fibers in the ventrolateral, ventromedial, and left stellate close cardiac nerves distal to the stellate ganglion resulted in the evoking of Aδ and C fibers potentials for each nerve stimulated. A predominance of C-fiber potentials in comparison to Aδ potentials was observed for each nerve, from dog to dog. This result correlates well with earlier anatomical evidence. Most potentials were recorded from the T3 white ramus, with little activity obtained from the sympathetic chain below that level. The presence of the left stellate cardiac nerve, which was found in only 40% of the dogs, appeared to dictate the distribution of afferent fibers to the VLCN. In the absence of the SCN, the number of potentials obtained from the VLCN was greatly increased relative to that o...