Effect of hypercapnia on blood brain barrier in rats with severe hypoxic-ischemic brain injury / 临床麻醉学杂志

ABSTRACT

Objective To investigate the effect of hypercapnia on hypoxic-ischemic brain injury in rats.Methods Forty-eight adult male SD rats were randomly divided into three groups: sham group (group S), hypoxic ischemic group (group HI) and hypercapnia group (group HP), n=16 in each group.Levine`s model was used to cause hypoxic-ischemic brain injury.In group S, the left common carotid artery was separated without ligation for 1 h, then ventilation with air maintaining the normal levels of PaO2 and PaCO2 for 3 h.In group HI, the left common carotid artery was separated and ligated for 1 h, PaO2 was maintained at 30-49 mm Hg by ventilating with low concentration (11%-13%) O2 for 3 hours.Based on group HI, PaCO2 in group HP was maintain at 60-80 mm Hg by inhalation of mixture gas containing (11%-13%) O2-8%CO2-N2 for 3 hours.FITC-dextran was used to measure the permeability of blood-brain barrier, TUNEL staining were used to observe the changes in the structure of the cerebral cortex.The expressions of aquaporin AQP4 and RECA-1 in cerebral cortex were detected by immunofluorescence and western blot.Results The level of brain water content, permeability of blood brain barrier and AQP4 expression were significantly increased in group HP as compared with group S and group HI (P<0.05).The histopathologic damage,as well as neuronal apoptotic index were aggravated in group HP as compared with group HI (P<0.05).Conclusion Hypercapnia may aggravate the brain damage during severe hypoxic-ischemic brain injury.This may associate with the increased expression AQP4 and the damage of blood-brain barrier.