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

将戊巴比妥钠麻醉动物制备成颅窗标本，用于测量脑膜血管直径。实验按以下方案进行：(1)观察氯胺酮对异氟醚和七氟醚脑血管反应的影响。氯胺酮本身不会引起脑血管扩张。全身给药氯胺酮可减弱异氟醚和七氟醚对软脑膜血管的扩张作用，并减弱软脑膜对PaCO2的反应。(2)比较常温和低温条件下局部应用右旋美托咪定对软脑膜血管管径的影响，常温条件下局部应用10℃和10℃~5&GT；M和10^~(-5)M可引起脑膜血管扩张，而在低温条件下局部应用相同浓度的右旋美托咪定可引起脑膜血管收缩。在常温和低温条件下，较高浓度的右美托咪定(10^~(-3)和~(-3)M)均可引起脑血管扩张。

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.