Cabanac M
Département de Physiologie, Faculté de Médecine, Université Laval, Québec, Canada.
FASEB J. 1993 Sep;7(12):1143-6; discussion 1146-7. doi: 10.1096/fasebj.7.12.8375612.
A mechanism that selectively cools the brain during hyperthermia is a well-accepted fact in animals. Selective brain cooling (SBC) during hyperthermia has also been proposed in humans, but this suggestion has met with considerable debate. Several authors have rejected the idea of human SBC for the following reasons: 1) SBC is illogical because this mechanism removes the error signal activating the defense against hyperthermia; 2) unlike other animals, humans do not pant and thus do not possess a powerful heat sink at a short distance from the brain; 3) humans do not have a carotid rete, the countercurrent heat exchanger between the arterial and venous bloods flowing in and out of the brain; 4) the high and constant arterial blood flow of the brain is sufficient to cool the brain under all conditions; and 5) the relatively low tympanic temperature (Tty) recorded in hyperthermic humans is not a sign of SBC, but rather is the sign of contamination of Tty by a low head skin temperature. These arguments are reviewed and rejected and results of several recent experiments are summarized. Finally, recent experimental articles that contradict the existence of human SBC or the validity of Tty are discussed and their conclusions refuted. This review points to overwhelming evidence in favor of human SBC.
在动物中，一种在体温过高时选择性冷却大脑的机制是被广泛接受的事实。体温过高时的选择性脑冷却（SBC）在人类中也已被提出，但这一观点引发了相当多的争论。几位作者基于以下原因否定了人类SBC的观点：1）SBC不合逻辑，因为这种机制会消除激活针对体温过高的防御的错误信号；2）与其他动物不同，人类不会喘气，因此在离大脑很近的地方没有强大的散热器官；3）人类没有颈动脉 rete，即进出大脑的动脉血和静脉血之间的逆流热交换器；4）大脑高且恒定的动脉血流足以在所有情况下冷却大脑；5）在体温过高的人类中记录到的相对较低的鼓膜温度（Tty）不是SBC的标志，而是Tty被低头部皮肤温度污染的标志。本文对这些论点进行了审视并予以否定，并总结了最近几项实验的结果。最后，讨论了最近与人类SBC的存在或Tty的有效性相矛盾的实验文章，并驳斥了它们的结论。这篇综述指出了支持人类SBC的压倒性证据。
