Moriyama E, Salcman M, Broadwell R D
Division of Neurological Surgery, University of Maryland School of Medicine, Baltimore.
Surg Neurol. 1991 Mar;35(3):177-82. doi: 10.1016/0090-3019(91)90068-k.
The effect of microwave-induced hyperthermia on the blood-brain barrier was studied in 21 Sprague-Dawley rats. Under sodium pentobarbital anesthesia, animals were place in a stereotactic frame, and an interstitial microwave antenna operating at 2450 MHz was inserted in a bony groove drilled parallel to the sagittal suture. Some antennae were equipped with an external cooling jacket. Temperature measurements were made lateral to the antenna by fluoroptical thermometry, and power was calculated from the time-temperature profile. Five minutes prior to termination of microwave irradiation, horseradish peroxidase (1 mg/20 g body weight) was injected intravenously. Extravasation of horseradish peroxidase was observed in brain tissue heated above 44.3 degrees C for 30 minutes and at 42.5 degrees C for 60 minutes. Microwave irradiation failed to open the blood-brain barrier when brain temperatures were sustained below 40.3 degrees C by the cooling system. Extravasation of blood-borne peroxidase occurred at sites of maximal temperature elevation, even when these did not coincide with the site of maximum power density. The data suggest that microwave-induced hyperthermia is an effective means for opening the blood-brain barrier and that the mechanism is not related to the nonthermal effect of microwaves.
在21只Sprague-Dawley大鼠中研究了微波诱导的高温对血脑屏障的影响。在戊巴比妥钠麻醉下，将动物置于立体定向框架中，并将一根工作频率为2450 MHz的间质微波天线插入平行于矢状缝钻出的骨槽中。一些天线配备了外部冷却套。通过荧光光学测温法在天线侧面进行温度测量，并根据时间-温度曲线计算功率。在微波辐射终止前5分钟，静脉注射辣根过氧化物酶（1 mg/20 g体重）。在脑组织加热至44.3摄氏度以上30分钟和42.5摄氏度60分钟时，观察到辣根过氧化物酶的外渗。当冷却系统使脑温维持在40.3摄氏度以下时，微波辐射未能打开血脑屏障。血源性过氧化物酶的外渗发生在温度升高最大的部位，即使这些部位与最大功率密度部位不一致。数据表明，微波诱导的高温是打开血脑屏障的有效手段，其机制与微波的非热效应无关。
