Intracellular brain pH, cortical blood flow (CBF), and electrocorticograms were recorded in regions of severe and moderate
ischemia in 10 control rabbits and 10 rabbits given
mannitol, 1 gm/kg, after occlusion of a major branch of the middle cerebral artery. Pooling the data from all 20 animals, preocclusion CBF was 46.4 +/- 3.6 ml/100 gm/min and intracellular brain pH was 7.01 +/- 0.04 (means +/- standard error of the means). Although
mannitol administration mildly improved CBF in regions of severe
ischemia, this increase was not sufficient to prevent metabolic deterioration as assessed by brain pH. However, in regions of moderate
ischemia, CBF improved significantly with
mannitol and the gradual decline in brain pH observed in control animals was prevented. For example, in the treated moderate
ischemia sites 4-hour postocclusion CBF and pH values were 31.8 ml/100 gm/min and 6.89 +/- 0.09, respectively, as compared to control values of 14.3 ml/100 gm/min and 6.75 +/- 0.06. These results suggest that
mannitol may be of benefit in stabilizing regions of moderate, but not severe,
ischemia after vessel occlusion.