Savola M K, MacIver M B, Doze V A, Kendig J J, Maze M
Department of Anesthesia, Stanford University School of Medicine, CA 94305-5123.
Brain Res. 1991 May 10;548(1-2):23-8. doi: 10.1016/0006-8993(91)91101-6.
Alpha 2-adrenoceptor agonists such as clonidine are sedatives and enhance the effectiveness of several different kinds of anesthetics. This study was performed to quantitate the effect of dexmedetomidine, a novel alpha 2-adrenoceptor agonist, on the action of the volatile anesthetic agent isoflurane in rats in vivo. A separate set of experiments in rat hippocampal slices was designed to determine whether isoflurane and dexmedetomidine exerted similar effects on synaptic transmission in vitro and to examine the interaction between the two agents. In vivo, dexmedetomidine (100 micrograms/kg i.p.) reduced isoflurane minimum alveolar anesthetic requirement (MAC), determined by loss of response to tail pinch, by approximately 90%. In hippocampal CA1 neurons, on the other hand, there was a relatively small potentiation of the effects of isoflurane at the maximally effective dexmedetomidine concentration (1 nM). The hippocampal CA1 area, at least in the slice preparation, may thus not be representative of the CNS site(s) at which alpha 2 adrenoceptor agonists lessen anesthetic requirement in vivo.
可乐定等α2 -肾上腺素能受体激动剂具有镇静作用，可增强多种不同类型麻醉剂的效果。本研究旨在定量新型α2 -肾上腺素能受体激动剂右美托咪定对大鼠体内挥发性麻醉剂异氟烷作用的影响。设计了另一组大鼠海马切片实验，以确定异氟烷和右美托咪定在体外对突触传递是否有相似作用，并研究这两种药物之间的相互作用。在体内，通过夹尾反应消失来确定，右美托咪定（100微克/千克腹腔注射）使异氟烷的最低肺泡有效浓度（MAC）降低了约90%。另一方面，在海马CA1神经元中，在最大有效右美托咪定浓度（1纳摩尔）时，异氟烷的作用仅有相对较小的增强。因此，至少在脑片制备中，海马CA1区可能不代表α2肾上腺素能受体激动剂在体内降低麻醉需求的中枢神经系统部位。
