Yamamoto Kenta, Kawada Toru, Kamiya Atsunori, Takaki Hiroshi, Sugimachi Masaru, Sunagawa Kenji
Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan.
Am J Physiol Heart Circ Physiol. 2005 Oct;289(4):H1604-9. doi: 10.1152/ajpheart.00053.2005. Epub 2005 May 20.
Elucidation of the interaction between the muscle mechanoreflex and the arterial baroreflex is essential for better understanding of sympathetic regulation during exercise. We characterized the effects of these two reflexes on sympathetic nerve activity (SNA) in anesthetized rabbits (n = 7). Under open-loop baroreflex conditions, we recorded renal SNA at carotid sinus pressure (CSP) of 40, 80, 120, or 160 mmHg while passively stretching the hindlimb muscle at muscle tension (MT) of 0, 2, 4, or 6 kg. The MT-SNA relationship at CSP of 40 mmHg approximated a straight line. Increase in CSP from 40 to 120 and 160 mmHg shifted the MT-SNA relationship downward and reduced the response range (the difference between maximum and minimum SNA) to 43 +/- 10% and 19 +/- 6%, respectively (P < 0.01). The CSP-SNA relationship at MT of 0 kg approximated a sigmoid curve. Increase in MT from 0 to 2, 4, and 6 kg shifted the CSP-SNA relationship upward and extended the response range to 133 +/- 8%, 156 +/- 14%, and 178 +/- 15%, respectively (P < 0.01). A model of algebraic summation, i.e., parallel shift, with a threshold of SNA functionally reproduced the interaction of the two reflexes (y = 1.00x - 0.01; r(2) = 0.991, root mean square = 2.6% between estimated and measured SNA). In conclusion, the response ranges of SNA to baroreceptor and muscle mechanoreceptor input changed in a manner that could be explained by a parallel shift with threshold.
阐明肌肉机械反射与动脉压力反射之间的相互作用，对于更好地理解运动过程中的交感神经调节至关重要。我们在麻醉兔（n = 7）中研究了这两种反射对交感神经活动（SNA）的影响。在开环压力反射条件下，我们在颈动脉窦压力（CSP）为40、80、120或160 mmHg时记录肾交感神经活动，同时以0、2、4或6 kg的肌肉张力（MT）被动拉伸后肢肌肉。在40 mmHg的CSP下，MT-SNA关系近似为一条直线。CSP从40 mmHg增加到120 mmHg和160 mmHg时，MT-SNA关系向下移动，响应范围（最大和最小SNA之间的差异）分别降至43±10%和19±6%（P < 0.01）。在0 kg的MT下，CSP-SNA关系近似为S形曲线。MT从0 kg增加到2、4和6 kg时，CSP-SNA关系向上移动，响应范围分别扩大到133±8%、156±14%和178±15%（P < 0.01）。一个代数求和模型，即平行移位，其SNA阈值在功能上再现了两种反射的相互作用（y = 1.00x - 0.01；r² = 0.991，估计和测量的SNA之间的均方根 = 2.6%）。总之，SNA对压力感受器和肌肉机械感受器输入的响应范围以一种可以用带阈值的平行移位来解释的方式发生变化。
