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

用戊巴比妥麻醉动物，在颅窗制备中测量脑脑血管直径。我们根据以下方案调查实验。(1)探讨氯胺酮对异氟醚和七氟醚的脑血管反应的影响。;氯胺酮本身不引起脑血管扩张。异氟醚和七氟醚所致的脑脊膜血管舒张可通过全身给药氯胺酮减弱，脑脊膜血管对PaCO2的反应也可减弱。(2)比较常温和低温条件下外用右美托咪定对脑血管直径的影响；在常温条件下，局部给予10^<-7> M和10^<-5> M右美托咪定可引起脑血管舒张，而在低温条件下，局部给予相同浓度的右美托咪定可引起脑血管收缩。在常温和低温条件下，右美托咪定的较高浓度（10^<-3>M）均可引起脑血管舒张。

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.