Cardiac sympathetic control of heart excitation rhythm in conscious cats

在这项研究中，我们检查了心脏交感神经活动(CSNA)是否传递心脏特有的神经信息，而不是肾脏等其他器官。为了解决这个问题，我们测量了CSNA，平均动脉压(MAP)和心率(HR)24小时，使用自由活动清醒猫结合自主神经阻断。在400 Hz频率下采集CSNA、MAP和HR，并在24小时内逐次计算其在6 S以上的平均值。对24小时的数据进行多元相关分析。CSNA和HR在24小时内的频率分布直方图呈多峰分布，而AP呈单峰分布。CSNA与心率呈显著正相关，心得安使心率减弱，而阿托品对心率无影响。CSNA与MAP也呈正相关，相关系数(0.3~0.4)小于CSNA与HR的相关系数(0.7)。如果肾交感神经活动(RSNA)与肾血流动力学和/或肾功能的改变有关，而不是与心功能相关，则RSNA、HR和MAP之间的关系必须改变。事实上，尽管RSNA与HR显著正相关，但相关系数(0.4)小于CSNA与HR的关系。结论：心脏交感神经活动是24小时心脏兴奋节律的主要决定因素之一，它传递的是心脏而不是肾脏等其他器官的特有神经信息。交感神经系统似乎对单个器官的生理功能起着不同的和特定的控制作用。

In this study we examined whether cardiac sympathetic nerve activity (CSNA) conveys neural information specific for the heart, rather than other organs such as the kidneys. To solve this, we measured CSNA,mean arterial blood pressure (MAP), and heart rate (HR) for 24 hour using freely moving conscious cats in combination with autonomic blockades. CSNA,MAP,and HR were sampled at 400 Hz and their mean values over 6 s were sequentially calculated over a 24 hour period. A multivariate correlation analysis was performed fro the 24-hour data. The frequency distribution histograms of CSNA and HR over a 24 hour period were multimodal, while the distribution of AP was unimodal. CSNA had a significant positive correlation with HR,which was blunted by propranolol but not by atropine. CSNA also had a positive correlation with MAP,whose coefficient (0.3-0.4) was smaller than the relationship between CSNA and HR (correlation coefficient, 0.7). If renal sympathetic nerve activity (RSNA) should be related to changes in renal hemodynamics and/or renal function rather than cardiac function, the relationships between RSNA,HR,and MAP must be changed from the relationships between CSNA,HR,and MAP.IN fact, although RSNA had a significant positive correlation with HR,the correlation coefficient (0.4) was smaller than the relationship between CSNA and HR.In conclusion, cardiac sympathetic nerve activity, which conveys neural information specific for the heart rather than the other organs such as the kidneys, is one of the predominant determinant of cardiac excitation rhythm during a 24 hour period. The sympathetic nervous sytem seems to perform a differential and specific control of the physiological function of individual organs.