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EFFECTS OF ANESTHETICS ON HYPOCAPNIA-INDUCED CONTRACTION OF ISOLATED CEREBRAL ARTERY

麻醉药对低碳酸血症引起的孤立性脑动脉收缩的影响

基本信息

批准号：
03454374
负责人：
HATANO Yoshio
金额：
$ 4.16万
依托单位：
WAKAYAMA MEDICAL COLLEGE
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03454374/
关键词：
Cerebral artery Carbon dioxide Cerebral bolld frow Halothane Isoflurane Sevoflurane ペントバルビタ-ル

项目摘要

Carbon dioxide is one of the most potent physiologic metabolites for regulation of cerebral blood flow. Both halothane and barbiturates have been shown to decrease cerebral matabolic rate (CMR), resulting in reduction of CO_2 production and thereby contraction of cerebral arteries. However, while barbiturates appear to maintain the normal relationship between CBF and CMR, halothane appears to possess the capacity to increase CBF.Weinvestigated the effects of anesthetics on hypocapnia-induced contraction of isolated dog cerebral artery.Arterial rings from cerebrai (basilar and middle cerebral) and mesenteric arteries were mounted in Krebs' Ringer solution aerated with 95% O_2 and 5% CO_2. Hypocapnia was induced by replacing the aerating gas mixture with 2.5% CO_2 and 97.5% O_2. Cerebral artery but not mesenteric artery contracted in response to hypocapnia. Removal of Ca^<2+> from extracellular fluid abolished the contraction. Endothelial denudation did not affect the contraction. The hypocapnia-induced contraction was attenuated by ezposure to halothane at 0.4, 0.7 and by pentobarbital only at high concectrations up to 3x10^4 M.The contraction induced by KCI 15mM was preferentially inhibited by pentobarbital rather than halothane. Isoflurane at 2.0 MAC also inhibited hypocapnia-induced contraction significantly while sevoflurane at 2 MCA failed to sffect the contraction. Among volatile anesthetics, the inhibitory effect on hypocapnia-induced contraction was in order of halothane > isoflurane > sevoflurane. It is suggested that metabolically mediated contraction of cerebral artery is inhibited during halothane to a greater extent than isoflurane and sevoflurane anesthesia, but is preserved during pentobarbital anesthesia.

二氧化碳是调节脑血流最有效的生理代谢物之一。氟烷和巴比妥类药物均已被证明可以降低脑代谢率 (CMR)，从而减少 CO_2 的产生，从而减少脑动脉收缩。然而，虽然巴比妥类药物似乎维持 CBF 和 CMR 之间的正常关系，但氟烷似乎具有增加 CBF 的能力。我们研究了麻醉药对低碳酸血症引起的离体狗大脑动脉收缩的影响。将大脑（基底动脉和大脑中动脉）和肠系膜动脉的动脉环固定在充气了 95% 的 Krebs' Ringer 溶液中 O_2和5%CO_2。通过用2.5％CO_2和97.5％O_2替换充气气体混合物来诱导低碳酸血症。脑动脉而非肠系膜动脉因低碳酸血症而收缩。从细胞外液中除去Ca 2+ 消除了收缩。内皮剥脱不影响收缩。低碳酸血症引起的收缩通过暴露于 0.4、0.7 的氟烷和仅在浓度高达 3x10^4 M 的戊巴比妥而减弱。KCI 15mM 诱导的收缩优先被戊巴比妥而非氟烷抑制。 2.0 MAC 的异氟醚也显着抑制低碳酸血症引起的收缩，而 2 MCA 的七氟醚未能影响收缩。挥发性麻醉药中，对低碳酸血症引起的收缩的抑制作用顺序为氟烷>异氟烷>七氟烷。表明代谢介导的脑动脉收缩在氟烷麻醉期间比异氟烷和七氟烷麻醉受到更大程度的抑制，但在戊巴比妥麻醉期间保留。