Localization of sympathetic and sensory neurons innervating the rat kidney

Following injection of horseradish peroxidase (HRP) into the hilar region of the left kidney of the rat, 66% of labeled sympathetic neurons were located in the ipsilateral paravertebral ganglia, with most cells in T13 and L1, and 14% were located in equivalent segments of the contralateral chain. A similar distribution of sympathetic neurons projected to the right kidney, with most cells in T12 and T13 paravertebral ganglia. Only 20% of the total sympathetic supply to either kidney arose from the prevertebral ganglia. The renal sensory innervation was also bilateral in origin, with about 80% of the neurons arising from ipsilateral dorsal root ganglia. Injection of HRP into the caudal and rostral poles of the left kidney labeled paravertebral neurons which were concentrated in ganglia L1 and T13, respectively, but did not label any sensory neurons. We conclude that most of the renal sympathetic innervation is paravertebral in origin, and that a substantial bilateral component exists for both sympathetic and sensory supplies. Neurons arising from the contralateral side have their cell bodies in segments that provide the main ipsilateral innervation to the same kidney. The majority of sensory axons appear to be restricted to subcortical areas.