Evidence for central chemoreception in the midline raph[acute]e
chemoreception in the raph[acute]e.
Bernard, David G., Aihua Li, and Eugene E. Nattie.
Department of Physiology, Dartmouth Medical School, Lebanon, New
Hampshire 03756-0001
APStracts 2:0389A, 1995.
We injected acetazolamide (AZ) (5 x 10-6 M, N=14, one nl), its
inactive analogue (AN) (2-Acetylamino-1,3,4-thiadiazole-5-sulfon-t
-butylamide, 5x10-5M, N=6), or mock cerebrospinal fluid (mCSF, N=5)
into the caudal raph[acute]e in the midline brainstem of
anesthetized, paralyzed, ventilated rats. These AZ injections have
been shown to produce a focal region of tissue acidosis with radius
< 350 [mu]m and are used as a probe for sites of central
chemosensitivity. Compared to control injections, AZ injection into
the raph[acute]e, as demonstrated by anatomical analysis of injection
location, significantly increased the amplitude of the integrated
phrenic neurogram over 10-40 mins. Not all raph[acute]e injections
produced such a response. AZ injections identified as responders (N=8
of 14) increased integrated phrenic amplitude 43.3 % +/- 10.7 % (SEM)
of baseline at 20 mins following the injection. We conclude that the
midline caudal raph[acute]e contains sites of ventilatory
chemoreception.
Received 27 March 1995; accepted in final form 4 August 1995.
APS Manuscript Number A328-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.