Regional brain uptake of noradrenaline following mechanical or osmotic opening of the blood-brain barrier.
The passage of noradrenaline from the cerebrovascular circulation into the brain (vessel walls and parenchyma) was studied quantitatively and regionally by a modification of Oldendorf's technique for determination of brain uptake index. Using 14C-ethanol as the highly diffusible internal standard, the index for noradrenaline varied between 2.7 and 4.5% in different regions, confirming the poor penetration of this neurotransmitter. The barrier was impaired transiently as evidenced by Evans blue extravasation, through osmotic opening by internal carotid injection of a hyperosmolar urea solution or mechanical disruption by a short-lasting elevation of the intracarotid hydrostatic pressure. This resulted in a 3-4-fold increase in the passage of noradrenaline from the circulation into the brain.
D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D006874:Hydrostatic Pressure; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D009997:Osmotic Pressure; D051381:Rats; D014508:Urea / Q000494:pharmacology
D014508:Urea; D009638:Norepinephrine