Kenney M J, Claassen D E, Bishop M R, Fels R J
Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66506, USA.
Am J Physiol. 1998 Dec;275(6):R1992-2001. doi: 10.1152/ajpregu.1998.275.6.R1992.
Frequency-domain analyses were used to determine the effect of heat stress on the relationships between the discharge bursts of sympathetic nerve pairs and sympathetic and phrenic nerve pairs in chloralose-anesthetized rats. Sympathetic nerve discharge (SND) was recorded from the renal, splanchnic, splenic, and lumbar nerves during increases in core body temperature (Tc) from 38 to 41.4 +/- 0. 3 degreesC. The following observations were made: 1) hyperthermia transformed the cardiac-related bursting pattern of SND to a pattern that contained low-frequency, non-cardiac-related bursts, 2) the pattern transformation was uniform in regionally selective sympathetic nerves, 3) hyperthermia enhanced the frequency-domain coupling between SND and phrenic nerve bursts, and 4) low-frequency SND bursts recorded during hyperthermia contained significantly more activity than cardiac-related bursts. We conclude that acute heat stress profoundly affects the organization of neural circuits responsible for the frequency components in sympathetic nerve activity and that SND pattern transformation provides an important strategy for increasing the level of activity in sympathetic nerves during increased Tc.
采用频域分析来确定热应激对水合氯醛麻醉大鼠交感神经对放电爆发以及交感神经与膈神经对之间关系的影响。在核心体温（Tc）从38℃升至41.4±0.3℃的过程中，记录肾神经、内脏神经、脾神经和腰神经的交感神经放电（SND）。得出以下观察结果：1）体温过高将与心脏相关的SND爆发模式转变为包含低频、与心脏无关的爆发模式；2）在区域选择性交感神经中，模式转变是一致的；3）体温过高增强了SND与膈神经爆发之间的频域耦合；4）体温过高期间记录到的低频SND爆发比与心脏相关的爆发包含更多的活动。我们得出结论，急性热应激深刻影响负责交感神经活动频率成分的神经回路组织，并且SND模式转变为在Tc升高期间增加交感神经活动水平提供了重要策略。
