Local cerebral blood flow and glucose utilization after blood exchange with a hemoglobin-based O2 carrier in conscious rats.
The effects of a blood exchange on cerebral blood flow and glucose utilization were studied. A near to total blood exchange (hematocrit < 3%) was achieved in conscious rats by isovolemic hemodilution. Ultrapurified, polymerized, bovine hemoglobin (UPBHB) served as a blood substitute. Local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU) were measured in 34 brain structures of conscious rats by means of the ido[14C]antipyrine and the 2-[14C]-deoxy-D-glucose methods. A group of rats without blood exchange served as control. After blood exchange LCBF increased from 36 to 126% in the different brain structures resulting in a nearly doubled mean cerebral blood flow (+82%). LCGU increased only moderately by 0-24%. Significant increases in LCGU were observed in 16 brain structures. Mean cerebral glucose utilization slightly increased (+14%). The relationship between LCGU and LCBF was found to be tight both in the control group (r = 0.95) as well as after blood replacement (r = 0.94), although it was reset to a higher overall LCBF-to-LCGU ratio. The profound increases in LCBF observed after blood exchange, which were not paralleled by comparable increases in LCGU, might be explained by a reduction of blood viscosity after blood exchange. Additional effects of blood exchange observed in the present study were an increase of mean arterial blood pressure and a decline of heart rate. The results indicate that replacement of blood with the hemoglobin-based oxygen carrier UPBHB appears to meet the cerebral circulatory and metabolic demands of the brain tissue.
Waschke
K
K
Institut für Anästhesiologie und Operative Intensivmedizin, Klinische Fakultät Mannheim, Universität Heidelberg, Germany.
Schröck
H
H
Albrecht
D M
DM
van Ackern
K
K
Kuschinsky
W
W
D000818:Animals; D000983:Antipyrine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation; D005947:Glucose / Q000378:metabolism*; D006438:Hemodilution; D006454:Hemoglobins; D008297:Male; D010951:Plasma Exchange; D011108:Polymers; D051381:Rats; D017207:Rats, Sprague-Dawley
D006454:Hemoglobins; D011108:Polymers; C080663:polymerized bovine hemoglobin; D005947:Glucose; D000983:Antipyrine; C008135:iodoantipyrine