Effects of MK-801 on Cerebral Regional Oxygen Consumption in Focal Cerebral Ischemia in Rats

This investigation tested in rats whether MK-801, an N-methyl-D-aspartate receptor antago-nist, would improve the balance of oxygen supply and consumption in the focal ischemic area of the brain induced by occlusion of the middle cerebral artery. Fifteen minutes after middle cerebral artery occlusion, 5 mg/kg MK-801 was administered intravenously to the MK-801 group (n=12), and normal saline was given to the control group (n=12). One hour after the occlusion in each group, regional cerebral blood flow was determined in six rats using [14C]iodoantipyrine, and regional arterial and venous oxygen saturations were determined using a microspectrophotometric technique in the other six rats. In both groups of animals, the cerebral blood flow of the ischemic cortex was significantly lower than that of the contralateral cortex (36±+16 [SD] and 67±+14 ml/min/100 g for the control group; 33±t10 and 58±+11 ml/min/100 g for the MK-801 group, respectively). Oxygen extraction was significantly higher in the ischemic cortex (8.8±2.1 ml 02/100 ml blood) than in the contralateral cortex (5.6+0.3) for the control group. However, for the MK-801 group, there was no significant difference between the ischemic cortex (6.1±+1.0) and the contralateral cortex (5.7±+1.1). Oxygen extrac-tion in the ischemic cortex of the MK- 801 group was significantly lower than that of the contro