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The effects of naloxone on anesthetized cats with focal cerebral ischemia, induced by middle cerebral artery(MCA) clipping through the transorbital approach, were studied. In five cats of sham control group, physiologic saline was infused intravenously after left eyeball enucleation. Five other cats, in which physiologic saline was infused after left MCA occlusion, served as control group. Also, naloxone was administered intravenously to another six cats. Twenty minutes later, a bolus intravenous injection of 10mg/kg of naloxone was done, This was followed by a 2mg/kg/hr 3 hour continuous intravenous infusion. A neurologic examintion was performed just before decapitation and the head was stored in a deep freezer immediately at -70℃. Brain Parenchyme was sampled in each “central core area” of MCA territory. Cytochrome oxidase activities and lipid peroxidation were measured by the Hess & Pope method and the E.D. Willis method respectively. The results were variable and the physiologic condition was also unstable. This was ascrbed to the irregularity of respiration and BP. Some cats showed stable vital signs and gas analysis We supposed that the increase of cytochrome oxidase activity and the decrease of lipid peroxidation in the stable group were caused by the naloxone effect. If a ventilator and physiography were used to maintain stable vital signs, and timing and dosage of naloxone adminsitration were considered, statistically more valuable data could be obtained. Also, further evaluation and study about other drugs such as MP, mannitol, indomethacin, Ca^(++) antagonists and K-opiate receptor agonists are needed
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