AJP - Heart and Circulatory Physiology, Vol 260, Issue 3 902-H908, Copyright © 1991 by American Physiological Society
Stimulation of area postrema decreases blood flow to choroid plexus
J. L. Williams, M. M. Thebert, K. A. Schalk and D. D. Heistad
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
The goal of this study was to examine effects of stimulation of the area
postrema on blood flow to choroid plexus and brain. In
chloralose-anesthetized dogs, the area postrema was stimulated
electrically, and arterial pressure and blood gases were maintained at
control levels. We measured blood flow to brain and choroid plexus of the
fourth and lateral ventricles with microspheres. Stimulation of the area
postrema at 10 +/- 2 microA (means +/- SE), which was the threshold for
changes in arterial pressure and heart rate, decreased blood flow to
choroid plexus of the fourth and lateral ventricles by 41 +/- 11 and 51 +/-
6%, respectively (from 349 +/- 38 and 503 +/- 46 ml.min-1.100 g-1,
respectively). Stimulation at high amplitudes (67 +/- 5 microA) produced
only slightly greater decreases in blood flow to choroid plexus. In
contrast, cerebral blood flow did not change during stimulation of the area
postrema. After blockade of autonomic ganglia with intravenous
chlorisondamine, stimulation of the area postrema had minimal effects on
blood flow to choroid plexus. The results indicate that stimulation of the
area postrema decreases blood flow to choroid plexus, probably by an
autonomic mechanism. We speculate that the area postrema may play a role in
regulation of volume in the central nervous system by modulating production
of cerebrospinal fluid.
