AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 1 113-R119, Copyright © 1985 by American Physiological Society
Properties of renobulbar afferent fibers in rats
M. M. Knuepfer and L. P. Schramm
Myelinated renobulbar sensory fibers project directly from the kidney to
the dorsomedial medulla. They can be activated by punctate stimulation of
the kidney. In these experiments we studied the physiological modality and
the intrarenal locations of the receptors for renobulbar fibers. Renobulbar
fibers were identified in recordings from the renal nerves of anesthetized
rats. Although nonmyelinated renal afferent fibers were activated by
increased intrarenal pressure and by chemical stimuli, no renobulbar fiber
activated by punctate mechanical stimulation was activated by these other
stimuli. Occasionally single fibers could be activated by punctate
stimulation of two or more sites on the surface of the kidney, and
responses from each site could be selectively blocked with a local
anesthetic. Renobulbar fibers could be activated by electrical stimulation
of discrete regions deep within the renal parenchyma. Increased intrarenal
pressure increased the sensitivity of receptors to punctate stimulation but
not to electrical stimulation of the kidney. We conclude that myelinated
renal afferent fibers in the rat respond to external mechanical stimuli,
lie deep within the renal parenchyma, and occasionally have more than one
receptor.
