AJP - Regulatory, Integrative and Comparative Physiology, Vol 263, Issue 2 412-R422, Copyright © 1992 by American Physiological Society
Renal afferent input to the ventrolateral medulla of the cat
M. A. Vizzard, A. Standish and W. S. Ammons
Department of Physiology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
Experiments were performed to determine if information from the kidneys
projects to the rostral ventrolateral medulla. Extracellular action
potentials were recorded from 148 cells within the rostral ventrolateral
medulla of alpha-chloralose-anesthetized cats. Cells within the rostral
ventrolateral medulla were tested for responses to electrical stimulation
of both left and right renal nerves. Electrical stimulation of renal nerves
excited 144 cells (97.3%) and inhibited 4. The majority of cells received
either bilateral or contralateral renal nerve input. Cells with bilateral
renal nerve input responded to contralateral renal nerve stimulation with a
significantly greater number of impulses compared with ipsilateral renal
nerve stimulation (P less than 0.05). All cells but one responding to renal
nerve stimulation had convergent somatic input. Comparisons between
thresholds for cell responses and activation thresholds for the A and C
volleys of the compound action potential recorded in the least splanchnic
nerve revealed that 44 cells required activation of A delta-fibers, and 12
cells required activation of both A delta- and C-fibers. A conditioning
stimulus applied to renal nerves on one side significantly decreased the
response elicited by a test stimulus applied to the renal nerves on the
opposite side for at least 300 ms (P less than 0.05). The demonstration
that an afferent connection exists between the kidneys and the
ventrolateral medulla suggests that the rostral ventrolateral medulla may
play a role in mediating supraspinal reflexes of renal origin.
