Pressure, volume, and chemosensitivity in the afferent innervation
of the urinary bladder in rats.
Moss, Nicholas G., W. Wallace Harrington, and M. Susan Tucker.
Department of Physiology, University of North Carolina, Chapel
Hill, NC 27599-7545
APStracts 3:0336R, 1996.
Bladder afferent nerve activity was recorded from the pelvic and
hypogastric nerves of rats anesthetized with sodium pentobarbital.
Bladder filling with isotonic NaCl at a rate of 250 [mu]l/min excited
multiunit afferent activity in the hypogastric nerve by 190+38% over
background at a pressure of 30 mmHg, whereas 150 mEq/l KCl at the
same filling rate excited hypogastric nerve activity by 498+103%
(p<0.0001). This difference was localized to a group of
chemosensitive fibers that are excited by bladder filling with KCl in
a concentration-dependent fashion, but are insensitive to bladder
filling with NaCl. Bladder filling with 200 mEq/l KCl at different
filling rates caused a bursting pattern of discharge in these fibers
at consistent bladder volumes but with a pressure threshold that
increased proportionately with filling rate. Other hypogastric
bladder afferent fibers were activated to a similar extent by NaCl
and KCl solutions. Chemoreceptive bladder afferent fibers were rare
in the pelvic nerve (1 of 15 units) and multiunit preparations showed
comparable excitations during bladder filling with NaCl and KCl
solutions. The bursting activation of bladder chemoreceptive afferent
nerves in hypogastric nerves could signal noxious overdistension
and/or inflammation of the bladder.
Received 7 May 1996; accepted in final form 13 August 1996.
APS Manuscript Number R256-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996