Flow indepenpent heterogeneity of brain capillary plasma perfusion
after blood exchange with a newtonian fluid.
Vogel, Johannes, Klaus F. Waschke, and Wolfgang Kuschinsky.
Department of Physiology and *Department of Anesthesiology and
Critical Care Medicine, Faculty of Clinical Medicine Mannheim,
University of Heidelberg, Germany
APStracts 3:0527H, 1996.
Previous studies of our group have indicated a heterogeneity of plasma
transit times in brain capillaries. The heterogeneity was decreased
with increasing cerebral blood flow during hypercapnia. In the
present study the hypothesis was tested that these apparent changes
in microvascular plasma perfusion heterogeneity depend on the
existence of red blood cells (RBCs). To this end, the blood of
anesthetized and paralyzed rats was replaced by a shear rate
independent oxygen-carrying substitute, ultrapurified, polymerized,
bovine hemoglobin (UPBHB). Cerebral blood flow (14C iodoantipyrine
technique) or microvascular perfusion pattern (i.v. bolus injection
of Evans blue and decapitation 3-4 seconds later) were measured.
After exchange trans fusion with UPBHB cerebral blood flow still
varied with arterial pCO2 whereas, in contrast to the unexchanged
condition, the heterogeneity of the intracapillary Evans blue
concentration remained unchanged. Compared to the unexchanged,
normocap nic condition the heterogeneity of intracapillary dye
concentration was decreased by one quarter. It is concluded that RBCs
contribute to the microvascular perfusion heterogeneity in the brain.
Received 12 August 1996; accepted in final form 4 December 1996.
APS Manuscript Number H731-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996