Tøien Ø, Mercer J B
Department of Arctic Biology, University of Tromsø, Norway.
J Comp Physiol B. 1998 Mar;168(2):73-80. doi: 10.1007/s003600050122.
Hypothalamic temperature (Thypo) and metabolic heat production (M) were measured in seven conscious rabbits injected intravenously with either saline or with Staphylococcus aureus, (8.10(7) cell walls.kg-1) while being subjected to a 3-h period of ramp-like total body cooling using a chronically implanted intravascular heat exchanger. In pyrogen-injected animals cooling started (1) at the time of injection or (2) 70 min after injection. In (1) the fall in Thypo induced by heat extraction was similar (1.0 degree C) in afebrile and febrile animals. In (2) there was a transient increase in Thypo of about 0.5 degree C at a time corresponding to the start of fever resulting in a significantly smaller fall in Thypo at the end of the 3-h cooling period (0.5 degree C vs 0.9 degree C, P < 0.05, n = 5). At this time in both (1) and (2) M was lower than theoretically expected from the increase in shivering threshold during fever. However, most of this effect can be explained when available data showing a decrease in thermosensitivity during S. aureus-induced fever are taken into account. After cessation of cooling in both groups of febrile animals Thypo rose to about 1 degree C higher than the precooling level, which is comparable to the fever level in a separate series of experiments with S. aureus injection without cooling (1.2 degrees C).
在七只清醒的兔子身上测量下丘脑温度（Thypo）和代谢产热（M），这些兔子通过长期植入的血管内热交换器接受3小时的斜坡式全身冷却，同时静脉注射生理盐水或金黄色葡萄球菌（8.10(7)细胞壁.kg-1）。在注射热原的动物中，冷却在（1）注射时开始或（2）注射后70分钟开始。在（1）中，发热和未发热动物中因热量提取引起的Thypo下降相似（1.0摄氏度）。在（2）中，在对应于发热开始的时间，Thypo有短暂升高约0.5摄氏度，导致在3小时冷却期结束时Thypo的下降明显更小（0.5摄氏度对0.9摄氏度，P < 0.05，n = 5）。在（1）和（2）的这个时候，M均低于根据发热期间寒战阈值升高理论预期的值。然而，当考虑到现有数据显示金黄色葡萄球菌诱导发热期间热敏感性降低时，这种效应的大部分可以得到解释。在两组发热动物停止冷却后，Thypo上升至比预冷却水平高约1摄氏度，这与在另一系列未冷却的金黄色葡萄球菌注射实验中的发热水平相当（1.2摄氏度）。
