Effects of viscosity and oxygen content on cerebral blood flow in ischemic and normal rat brain.
The mechanism of hemodilution-induced increases in cerebral blood flow (CBF) was investigated. Hemodilution was achieved with a molecular hemoglobin solution (DCLHb) and albumin which have similar viscosities but different oxygen carrying capacities. Part A: CBF was assessed in rats after one of the following regimens: (1) control-hematocrit not manipulated, (2) 30/Alb-hematocrit decreased to 30% with albumin, (3) 30/DCLHb-hematocrit decreased to 30% with DCLHb, or (4) 16/Alb/DCLHb-hematocrit decreased to 30% with albumin and then 16% with DCLHb. For viscosity matched groups (30/Alb and 30/DCLHb), CBF was greater in animals with decreased oxygen content (30/Alb); while in oxygen content matched groups (30/Alb and 16/Alb/DCLHb), CBF was greater in animals with decreased viscosity (16/Alb/DCLHb) (p < 0.05). Part B: Middle cerebral artery occlusion was performed, hemodilution achieved as in Part A, and CBF determined. For viscosity matched groups (30/Alb and 30/DCLHb), CBF was less in rats with decreased oxygen content (30/Alb); while in oxygen content matched groups (30/Alb and 16/Alb/DCLHb), CBF was greater in animals with decreased viscosity (16/Alb/DCLHb) (p < 0.05). This data supports the premise, that in normal brain, both viscosity and oxygen content effect CBF; while in ischemic brain, a decrease in viscosity but not oxygen content increases CBF.
Cole
D J
DJ
Department of Anesthesiology, Loma Linda University, CA 92354.
Drummond
J C
JC
Patel
P M
PM
Marcantonio
S
S
D000818:Animals; D001241:Aspirin / Q000031:analogs & derivatives / Q000494:pharmacology; D001345:Autoradiography; D001810:Blood Volume / Q000502:physiology; D001923:Brain Chemistry / Q000502:physiology*; D002545:Brain Ischemia / Q000378:metabolism / Q000473:pathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D006400:Hematocrit; D006438:Hemodilution; D006454:Hemoglobins / Q000494:pharmacology; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D011918:Rats, Inbred SHR; D012709:Serum Albumin / Q000494:pharmacology; D014783:Viscosity
D006454:Hemoglobins; D012709:Serum Albumin; C083478:diaspirin-cross-linked hemoglobin; D001241:Aspirin