EFFECTS OF ALPHA2-ADRENERGIC AGONISTS AND NMDA-ANTAGONISTS ON CEREBRAL MICROCIRCULATION UNDER THE HYPOTHERMIC CONDITION -ASSESSED WITH CLOSED CRANIAL WINDOW TECHNIQUE-.

准备戊巴比妥麻醉的动物用于在颅窗准备中测量脑软膜血管直径。我们根据以下方案研究实验。(1)探讨氯胺酮对异氟醚和七氟醚脑血管反应的影响。氯胺酮本身不引起脑血管扩张。氯胺酮可减弱异氟醚和七氟醚对软脑膜血管的舒张作用，并降低软脑膜血管对PaCO 2的反应性。(2)比较在常温或低温条件下局部给予右美托咪定对脑软脑膜血管直径的影响;在常温条件下，局部给予10 μ <-7>M和10 μ <-5>M右美托咪定诱导脑软脑膜血管舒张，而在低温条件下，局部给予相同浓度的右美托咪定诱导脑软脑膜血管收缩。在<-3>常温和低温条件下，较高浓度（10 μ M）的右美托咪定均诱导脑软膜血管舒张。

Pentobarbital anesthetized animals were prepared for measurement of cerebral pial vessel diameter in a cranial window preparation. We investigated the experiments according to following protocols.(1) To investigate the effect of ketamine on cerebrovascular response to isoflurane and sevoflurane. ; Ketamine itself did not induce cerebrovascular dilation. The vasodilation of cerebral pial vessels induced by isoflurane and sevoflurane could be attenuated by the systemic administration of ketamine, and the response of pial vessels to PaCO2 also attenuated.(2) To compare the effect of topical dexmedetomidine on cerebral pial vessel diameter under normothermic or hypothemic condition ; In normothermic condition the topical administration of 10^<-7> M and 10^<-5> M dexmedetomidine induced a vasodilation of cerebral pial vessels, whereas in hypothermic condition the topical administration of the same concentration of dexmedetomidine induced a vasoconstriction of cerebral pial vessels. The higher concentration (10^<-3>M) of dexmedetomidine induced a vasodilation of cerebral pial vessels in both normothermic and hypothermic condition.