Kenney M J, Claassen D E, Fels R J, Saindon C S
Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66506, USA.
J Appl Physiol (1985). 1999 Aug;87(2):732-42. doi: 10.1152/jappl.1999.87.2.732.
Frequency-domain analyses were used to determine the effect of cold stress on the relationships between the discharge bursts of sympathetic nerve pairs, sympathetic and aortic depressor nerve pairs, and sympathetic and phrenic nerve pairs in chloralose-anesthetized, baroreceptor-innervated rats. Sympathetic nerve discharge (SND) was recorded from the renal, lumbar, splanchnic, and adrenal nerves during decreases in core body temperature from 38 to 30 degrees C. The following observations were made. 1) Hypothermia produced nonuniform changes in the level of activity in regionally selective sympathetic nerves. Specifically, cold stress increased lumbar and decreased renal SND but did not significantly change the level of activity in splanchnic and adrenal nerves. 2) The cardiac-related pattern of renal, lumbar, and splanchnic SND bursts was transformed to a low-frequency (0-2 Hz) pattern during cooling, despite the presence of pulse-synchronous activity in arterial baroreceptor afferents. 3) Peak coherence values relating the discharges between sympathetic nerve pairs decreased at the cardiac frequency but were unchanged at low frequencies (0-2 Hz), indicating that the sources of low-frequency SND bursts remain prominently coupled during progressive reductions in core body temperature. 4) Coherence of discharge bursts in phrenic and renal sympathetic nerve pairs in the 0- to 2-Hz frequency band increased during mild hypothermia (36 degrees C) but decreased during deep hypothermia (30 degrees C). We conclude that hypothermia profoundly alters the organization of neural circuits involved in regulation of sympathetic nerve outflow to selected regional circulations.
在水合氯醛麻醉、有压力感受器支配的大鼠中，采用频域分析来确定冷应激对交感神经对、交感神经与主动脉减压神经对以及交感神经与膈神经对放电爆发之间关系的影响。在核心体温从38℃降至30℃的过程中，记录了肾神经、腰神经、内脏神经和肾上腺神经的交感神经放电（SND）。得出以下观察结果：1）体温过低会导致局部选择性交感神经的活动水平发生不均匀变化。具体而言，冷应激会增加腰交感神经放电而降低肾交感神经放电，但内脏神经和肾上腺神经的活动水平没有显著变化。2）在降温过程中，肾、腰和内脏神经SND爆发的心脏相关模式转变为低频（0 - 2Hz）模式，尽管动脉压力感受器传入神经中存在脉冲同步活动。3）交感神经对之间放电的峰值相干值在心脏频率处降低，但在低频（0 - 2Hz）处不变，这表明在核心体温逐渐降低期间，低频SND爆发的来源仍显著耦合。4）在轻度低温（36℃）期间，膈神经与肾交感神经对在0至2Hz频段的放电爆发相干性增加，但在深度低温（30℃）期间降低。我们得出结论，体温过低会深刻改变参与调节交感神经向特定区域循环流出的神经回路组织。
