Abstract
The mechanism responsible for the reduction of contralateral cerebral blood flow (CBF) and metabolism in early stage of unilateral hemispheric infarction in man has not been fully understood.
In order to investigate the above mechanism influences of unilateral global ischemia in 107 gerbils on contralateral CBF, water content, electrolytes and glucose metabolism were investigated.
Thirty minutes after ligation of the right common carotid artery, ipsilateral CBF decreased to less than 20ml/100g brain/min. Both water content and Na : K ratio increased and these changes were significantly correlated with the reduction of CBF.
In the contralateral hemisphere, CBF decreased from 51.0±7.9 to 42.3±11.4ml/100g br./min and water content increased significantly as early as thirty minutes after the ligation, but the Na : K ratio did not change during this period. Since the degree of the reduction of contralateral CBF was not large enough to produce brain edema by ionic disturbance, the increased water content of the contralateral hemisphere must be attributed to factors other than ionic disturbances.
Semiquantitative measurements of contralateral glucose utilization rate (GUR) by 14C-deoxyglucose showed two different patterns depending on severity of the ischemic symptoms.
In the animals with the mild or moderate symptoms, contralateral cerebral GUR did not change as compared with the control animals. On the contrary, in the animals with the severe symptoms, regions with an increase of GUR was observed in the contralateral hemisphere.
In conclusion, the contralateral reduction of CBF observed in the early phase of the unilateral ischemia was not always accompanied by the suppression of glucose matabolism. The above data are inconsistent with the “diaschisis” hypothesis where the transneural inhibition of metabolism is considered to be prerequisite to the reduction of contralateral CBF.
