Tracing the origin of the sympathetic afferent nerve of the ventriculus cordis by means of horseradish peroxidase method in the rat

Summary

Two to five μ1 20–50% horseradish peroxidase (HRP) in normal saline solution have been injected into the myocardium of the left ventricle of 36 rats. HRP positive reaction granules in spinal ganglion cells have been observed by means of DAB method.

• 1. The HRP labelled cells were localized in ganglions of the C₈-Th₈ spinal nerves in 9 rats. This indicates that ganglion cells of the spinal nerves send their peripheral processes as afferent fibers to the left ventricular wall of the heart. The origin of cardiac sympathetic afferent fibers in our experiment showed a much wider distribution than the general range of the Th₁-Th₅ spinal ganglions. However, the labelled cells contained in Th₁-Th₅ spinal ganglions amounted to 63.7% in our experiment.

• 2. The HRP reaction granules contained in spinal ganglion cells were chiefly medium and small in size.

• 3. The wider origin of cardiac sympathetic afferent fibers provides a possible morphological explanation for referred pain in some cases of angina pectoris.