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

我们假设，根据单个血管床或器官的生理功能，交感神经向不同血管床或器官的流出受到特异性和差异的控制。这种对交感神经系统的精细控制将通过日常生活中自愿行为中向不同器官（如心脏和肾脏）流出的交感神经的直接测量来揭示。因此，本研究旨在确定有意识猫在自愿行为时心脏交感神经活动（CSNA）和肾脏交感神经活动（RSNA）的反应，并确定CSNA与心输出量（CO）以及RSNA与总外周血管阻力（TPR）之间的因果关系。在心下神经或肾神经上植入一对电极，在升主动脉上放置多普勒血流探头。左颈动脉和颈静脉置入导管。术后3 ~ 10天，在无约束条件下，连续5小时同时测量CSNA或RSNA、升主动脉血流量、平均动脉压（MAP）和心率（HR）。依次计算CO、冲程体积（SV）和TPR。分析了交感神经和血流动力学对各种自愿行为（跑步机运动、饮食和睡眠）的反应。在跑步机上运动时，HR和CO随运动速度成比例增加。MAP在运动过程中以10-30 m/min的较慢速度变化不大，在运动过程中以40-50 m/min的较快速度逐渐上升。因此计算出的TPR在运动过程中有降低的趋势。心得安减弱了心动过速，几乎消除了跑步机运动期间CO的增加，表明心脏交感神经激活。的确，我们发现在跑步机上运动时，CSNA增加，这与HR和co的反应一致。有趣的是，在慢速运动时，RSNA没有变化，而在快速运动时，RSNA增加。与跑步机运动相比，MAP在进食和饮水时显著增加，而HR和CO略有增加，表明TPR显著增加。另一方面，睡眠时MAP明显下降，而HR和CO变化不大，提示TPR降低。与血流动力学反应一致，进食和饮水时RSNA增加，但在睡眠时被抑制；RSNA组的反应大于CSNA组。由此可见，在日常生活的各种自愿行为中，交感神经向心脏和肾脏的流出分别受到不同的调节，表明交感神经系统受到脑心血管中枢的精细控制。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