AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 3 435-R443, Copyright © 1986 by American Physiological Society
Renal afferent input to thoracolumbar spinal neurons of the cat
W. S. Ammons
Responses of 65 thoracolumbar spinal neurons to electrical stimulation of
the left renal nerves were examined in 19 cats anesthetized with
alpha-chloralose. Cells were found primarily in laminae V and VII of the
T12-L2 segments on the left side of the spinal cord. Renal nerve
stimulation excited 55 and inhibited 10 cells. Excitatory responses were
characterized either by short latency or both short and long latency
responses (means +/- SE: 13 +/- 1 and 68 +/- 7 ms). Recordings of the
compound action potential in the least splanchnic nerve indicated that
early responses resulted from A delta-renal afferent input and long latency
responses from C-fiber renal input. Maximal responses to A delta-renal
input (3.3 +/- 0.5 spikes/stimulus) were significantly greater than maximal
responses to C-fiber renal input (1.5 +/- 0.3 spikes/stimulus). Inhibitory
responses were best demonstrated by repetitive stimuli; however, responses
of five cells to single stimuli showed that these responses had long
latencies to onset (36 +/- 6 ms). All cells were excited or inhibited by
somatic stimuli. Excitatory somatic receptive fields invariably included
the left flank region and lower abdomen, occasionally included the left
hindlimb, and in a few cases included the right hindlimb. Thirteen cells
had both excitatory and inhibitory somatic receptive fields. The results
show that thoracolumbar spinal neurons receive renal A delta- and C-fiber
input that converges with input from somatic structures. These cells may
participate in renal pain which is referred to somatic structures or
reflexes initiated by renal afferent fibers.
