Altered cerebral glucose utilization following blood-brain barrier opening by hypertonicity or hypertension

The blood-brain barrier (B-BB) in conscious rats was opened to Evans blue dye by carotid infusion of a 1.8 m arabinose solution or by acute unilateral carotid hypertension, following which ¹⁴C]2-deoxy-d-glucose was injected intravenously. Rats were killed 45 min later, and autoradiographs were made from frozen brain sections. Focal areas of increased optical density, or “hot spots,” were noted in brain regions when the B-BB was opened but were absent when B-BB integrity was unaffected. These hot spots, which represented accumulations of brain radioactivity, were not prevented by diet-induced hypokalemia or by systemic pretreatment with high doses of phenoxybenzamine or propranolol. Their cause remains unclear, but their induction by both hypertensive and osmotic B-BB opening suggests that B-BB damage, regardless of cause, can markedly disturb cerebral metabolism.