AJP - Regulatory, Integrative and Comparative Physiology, Vol 253, Issue 3 425-R433, Copyright © 1987 by American Physiological Society
Effect of naloxone on regional cerebral blood flow during endotoxin shock in conscious rats
W. R. Law and J. L. Ferguson
Maintenance of cerebral blood flow (CBF) is vital during cardiovascular
shock. Since opioids have been implicated in the pathophysiology of
endotoxin shock and have been shown to alter cerebral perfusion patterns,
we determined whether opioids were responsible for any of the changes in
regional CBF observed during endotoxin shock and whether the use of
naloxone might impair or aid in the maintenance of CBF. When blood flow
(BF) is studied with microspheres in rats, the left ventricle of the heart
is often cannulated via the right carotid artery. Questions have arisen
concerning the potential adverse effects of this method on CBF in the
hemisphere ipsilateral to the ligated artery. We measured right and left
regional CBF by use of this route of cannulation. Twenty-four hours after
cannulations were performed, flow measurements were made using radiolabeled
microspheres in conscious unrestrained male Sprague-Dawley rats (300-400 g)
before and 10, 30 and 60 min after challenging with 10 mg/kg Escherichia
coli endotoxin (etx) or saline. Naloxone (2 mg/kg) or saline was given as a
treatment 25 min post-etx. We found no significant differences between
right and left cortical, midbrain, or cerebellar BF at any time in any
treatment group. After etx, the whole brain received a large share of the
depressed cardiac output. Thus global CBF was not significantly reduced
below its pre-etx value, an effect unaltered by naloxone. Regionally, BF
was reduced to cerebellum and midbrain by 30 min post-etx. Naloxone
prevented this depression. No region was affected to a greater or lesser
degree than others.(ABSTRACT TRUNCATED AT 250 WORDS)
