Hypervolemic-Hemodilution and Hypertension During Temporary Middle Cerebral Artery Occlusion in Rats: The Effect on Blood-Brain Barrier Permeability

Abstract

ABSTRACT:The effect of hypervolemic-hemodilution, with and without hypertension, on blood-brain barrier permeability was investigated in rats, after 180 minutes of middle cerebral artery occlusion (MCAo), and 60 minutes of reperfusion. One of the following conditions was maintained during MCAo: 1) Control — hematocrit and blood pressure were not manipulated; 2) Hypervolemic-Hemodilution/Normotension — the hematocrit was decreased to 30%; 3) Hypervolemic-Hemodilution/Hypertension — the hematocrit was decreased to 30% and mean arterial pressure increased by 30 mmHg with phenylphrine. In all groups, Evans Blue was administered, and its concentration determined by spectrophotometric assay. Evans Blue (μg{g-1 of brain tissue [mean ± SD]) was greater in the Hypervolemic- Hemodilution/Hypertension group (71 ± 20) versus the Control (13 ± 9) and Hypervolemic-Hemodilution/ Normotension (17 ± 10) groups (p < 0.05). No other differences were present. These results support the hypothesis that during MCAo, hypervolemic-hemodilution/hypertensive therapy effects an increase in blood-brain barrier permeability in the early period of reperfusion.

Focal Cerebral Ischemia in Rats: Effect of Hemodilution with α-α Cross-Linked Hemoglobin on Brain Injury and Edema

“…After approval by the institutional research committee, male, spontaneously hypertensive rats (350 -400 g, [16][17][18][19][20] Each rat was randomized to one of the following groups for which blood volume was increased by 8.0 ml (= 30%) and hematocrit (Hct) maintained at steady state throughout the study period. If DCLHb is initially given as an exchange transfusion normotension is maintained; however, if initially given as a rapid bolus mean arterial blood pressure [MABP] increases by 2 0 -3 0 mm Hg for = 180-min.…”

Verge: A Novel Vascular Early Response Gene

“…We examined the effect of focal ischemia on the expression of verge using a well characterized stroke model in which the middle cerebral artery of an adult mouse is transiently occluded by a filament that is threaded into the lumen of the vessel (Schneider et al, 1999). This model results in a transient disruption of the blood-brain barrier and increased vascular permeability (Cole et al, 1990;Betz et al, 1994). Transient focal ischemia (1.5 hr ischemia and 2 hr reperfusion) resulted in a threefold increase in verge mRNA expression in the ischemic hemisphere compared with the nonischemic hemisphere of the same animal (Fig.…”

Diaspirin Crosslinked Hemoglobin (DCLHbTM) does not Affect the Anesthetic Potency of Isoflurane in Rats

“…During low flow states (e.g.. cerebral ischemia), with damage to a blood-tissue barrier [33], it is believed that extravasation of hemoglobin increases [34]. During low flow states (e.g.. cerebral ischemia), with damage to a blood-tissue barrier [33], it is believed that extravasation of hemoglobin increases [34].…”