Effect of an acute increase of the intravascular pressure on the blood-brain barrier: a comparison between conscious and anesthetized rats.

Conscious rats and rats under nitrous oxide anesthesia were subjected to blood pressure elevations by injection of epinephrine, bicuculline and amphetamine. Mean arterial pressure was measured from a chronic indwelling cannula in the aorta in awake rats. The protein leakage in the brains was studied using Evans blue and 125IHSA. Conscious animals developed less blood-brain barrier dysfunction than anesthetized ones. The largest difference was obtained with amphetamine and the smallest with epinephrine. Possible explanations to the results are discussed.