Physiological results of monkey brain ischemia, and protection by a calcium blocker

Physiological and histological investigation was undertaken to examine dynamic and metabolic changes due to transient ischemic insult of the monkey brain with and without postischemic treatment by the calcium entry blocker, NC-1100 (1 mg/kg, IV). Monkeys were subjected to temporary occlusion of the eight major arteries: bilateral common carotid, internal and external carotid, and vertebral arteries. Blood flow was restored after 5-, 10-, 13-, and 15-min ischemia in different monkeys. The amplitudes of extradural, cortical, and hippocampal electroencephalograms decreased severely within 1-6 min after beginning occlusion. Complete recovery of these electroencephalograms required more than 1 h. During ischemia, significant change was obvious in arterial glucose, and systolic, diastolic, and mean blood pressure, all of which increased. There were no significant physiological differences between the untreated and NC-1100-treated groups, except decreased diastolic blood pressure and slightly lower postischemic heart rate in the treated group. These small differences might be accounted for by the effect of the calcium blocker. Ten to 15 minutes ischemia caused cell changes, including cell death, which were confined almost exclusively to the CA1 subfield of untreated hippocampi examined the fifth day after occlusion. However, no ischemia-induced cell change was observed in the CA1 subfield of hippocampi subjected to 10 to 15 min ischemia in the NC-1100-treated group. It was concluded that a calcium entry blocker can protect neurons from mild ischemia-induced injury and might ameliorate morphological damage and functional impairment of the brain due to ischemia in patients who suffer transient anoxic or hypoxic injury. The present physiological data should contribute to their clinical treatment.