Cardiac sympathetic nerve control of cardiac output during 24-hour period

我们假设，交感神经流出到不同的血管床或器官是根据单个血管床或器官的生理功能而特定和不同地控制的。在日常生活中，通过直接测量交感神经流出到不同器官(如心脏和肾脏)的交感神经活动，可以揭示交感神经系统的这种精细控制。因此，本研究旨在确定清醒猫在自愿行为时心脏交感神经活动(CSNA)和肾交感神经活动(RSNA)的反应，并确定CSNA与心输出量(CO)和RSNA与外周血管总阻力(TPR)之间的因果关系。在心下神经或肾神经植入一对电极，升主动脉放置多普勒血流探头。将导管插入左侧颈动脉和颈静脉。三到…术后10天以上，在自由状态下同时测量CSNA或RSNA、升主动脉血流量、平均动脉压(MAP)和心率(HR)。每搏输出量(SV)、心输出量(CO)、每搏输出量(TPR)。分析了不同自愿行为(跑步机运动、饮食和睡眠)的交感神经和血流动力学反应，在跑步机运动中，心率和CO随运动速度的增加而增加。MAP在10~30m/min的慢速运动中变化不大，在40~50m/min的较快速度运动中有逐渐升高的趋势。因此计算出的TPR在运动过程中呈下降趋势。心得安减弱了跑台运动时的心动过速，几乎完全消除了CO的增加，提示心脏交感神经的激活。事实上，我们发现CSNA在跑步机运动中增加，与HR和CO的反应一致。有趣的是，RSNA在慢速运动中没有变化，在快速度运动时增加。与跑步机运动相比，饮食时MAP显著升高，HR和CO略有升高，提示TPR显著升高。另一方面，睡眠时MAP显著下降，HR和CO变化不大，提示TPR降低。与血流动力学反应一致，RSNA在饮食中增强，但在睡眠中被抑制；RSNA的反应大于CSNA。结论：在日常生活中，交感神经流出到心脏和肾脏的交感神经流出是单独和有区别地调节的，这表明交感神经流出在日常生活中的各种自愿行为中是独立的和有区别的，提示交感神经系统受到脑血管中枢的良好控制。较少

We hypothesized that sympathetic outflows to different vascular beds or organs are specifically and differentially controlled in accordance with the physiological function of an individual vascular bed or organ. Such fine control of the sympathetic nervous system will be revealed by direct measurements of sympathetic outflows to different organs (such as the heart and the kidneys) during voluntary behavior in daily life.The present study was therefore undertaken to determine the responses in cardiac sympathetic nerve activity (CSNA) and renal sympathetic nerve activity (RSNA) during voluntary behavior in conscious cats and to identify the cause-effect relationships between CSNA and cardiac output (CO) and between RSNA and total peripheral vascular resistance (TPR). A pair of electrodes was implanted on the inferior cardiac nerve or the renal nerve and a Doppler flow probe was placed on the ascending aorta. Catheters were inserted into the left carotid artery and jugular vein. Three to … More ten days after the surgery, CSNA or RSNA, ascending aortic blood flow, mean arterial blood pressure (MAP) and heart rate (HR) were simultaneously measured for 5 hour in the unrestrained condition. CO, stroke volume (SV), and TPR were sequentially calculated. The sympathetic nerve and hemodynamic responses to a variety of voluntary behaviors (treadmill exercise, eating, drinking, and sleep) were analyzed.During treadmill exercise, HR and CO increased in proportion to the exercise speed. MAP did not change during exercise with a slow speed of 10-30 m/min and tended to rise gradually during exercise at a faster speed of 40-50 m/min. Thus calculated TPR tended to decrease during exercise. Propranolol blunted the tachycardia and almost abolished the increase in CO during treadmill exercise, suggesting cardiac sympathetic activation. Indeed, we found that CSNA increased during treadmill exercise, in accordance with the responses in HR and CO.It was interesting that RSNA showed no change during exercise at the slow speed and increased at the faster speed. In contrast to treadmill exercise, MAP increased considerably during eating and drinking while HR and CO increased slightly, suggesting a marked increase in TPR.On the other hand, MAP decreased considerably during sleep while HR and CO showed litle changes, suggesting a reduction in TPR.In consistent with the hemodynamic responses, RSNA was augmented during eating and drinking but was inhibited during sleep ; the responses in RSNA were greater than those in CSNA.It is concluded that sympathetic outflows to the heart and the kidneys are separately and differentially regulated during a variety of voluntary behaviors in daily life, suggesting fine control of the sympathetic nervous system by the brain cardiovascular center. Less