Heatpipe System for Thermal Stimulation of Organims.

点击翻译按钮获取中文摘要

Heating and cooling of local tissue of organisms are a major technique for thermophysiological study. Especially, thermal stimulation of the brain, which is one of the major site for detecting internal body temperature, has provided many important knowledges concerning the central mechanisms of body temperature regulation. At present, thermal stimulation of the brain is made mostly with a waterperfused thermode. This method, however, requires continuous water supply that inevitably restricts animal's behavior. Additionally, the thinnest thermode available is that with 0.8 mm diameter. And because thermal gradient along thermode is inevitable, it is difficult to make thermal stimulation only to a small volume. Stimulation with laser beam or high frequency current is also used, but only warming is possible with the method. In the present study, we tried to develop a small thermode especially for thermal stimulation of the brain, using a "heatpipe". In 1990, we succeeded in making a silver heatpipe of 25 mm length with 0.7 mm diameter. It was confirmed from neutron picture that this certainly works as a heatpipe. At one end of the heatpipe a module for heating and cooling, which consist of a small Peltier device (5 X 5 mm) and a cooling fin, was attached. Whole system weighed only 0.6 g. In 1991, we implanted this thermode into rat brain and tested for its capacity. At a brain temperature of --C^ﾟ the temperature could be changed by 1.3C^ﾟ at a Peltier device current of 0.6 A. The heatpipe thermode might be able to use for local coolin and heating of the organic tissues. But it is required to develope a round shaped Peltier device for getting a good heat flow from the device to the heatpipe, otherwise this small heatpipe can not be used for cooling.