Stinnett H, Wiggen T, Olson M, Ewert D
Department of Physiology, University of North Dakota, Grand Forks 58202.
Proc Soc Exp Biol Med. 1992 Jul;200(3):359-74. doi: 10.3181/00379727-200-43443.
This study examined multifiber baroreceptor nerve activity (BNA) as a function of carotid sinus wall distension in 19 rabbits. Analysis estimated mechanical or viscoelastic properties of the sinus wall and their influence on BNA. In six sinuses, properties were altered by treatment with the enzyme protease to remove the endothelium and with nifedipine to passively relax smooth muscle. Properties were estimated from dynamic and steady state wall response to a 45 mm Hg step increase and decrease in intrasinus pressure (ISP) of 20 min. Control wall response had fast and slow (creep) portions with a viscosity increase from 1,370 N(s)/m to 17,864 N(s)/m during step-up in ISP. Wall elasticity averaged 77 N/m; which estimated the relationship of force and change in steady state response. Control BNA response also had fast and slow (resetting) portions. A BNA and wall response relationship (BNA/m) was defined as transduction-gain (T-G) with proportional and dynamic components. In the subgroup, wall creep and baroreceptor resetting were abolished by protease treatment, suggesting an endothelial mediator which influenced sinus smooth muscle. Histology data indicated enzyme damage was limited to tunica intima tissues, and nifedipine did not block Ca2+ channels on neural structures. By comparison of responses before and after treatments the proportional component of T-G was equated to an elastic influence (1/E), with E = 7.5 x 10(-6) m/BNA, while the dynamic component was equated to a viscous influence (1/V), with V = 1.53 x 10(-4) m(s)/BNA. A simple but fundamental relationship for baroreceptor-tissue linkages was estimated by BNA/m = 1/(Vs + E), a first-order transfer function.
本研究在19只家兔中检测了多纤维压力感受器神经活动（BNA）作为颈动脉窦壁扩张功能的情况。分析估计了窦壁的力学或粘弹性特性及其对BNA的影响。在六个窦中，通过用蛋白酶处理以去除内皮以及用硝苯地平使平滑肌被动舒张来改变特性。通过对20分钟内窦内压（ISP）阶跃升高和降低45 mmHg时的动态和稳态壁反应来估计特性。对照壁反应有快速和缓慢（蠕变）部分，在ISP升高阶段粘度从1370 N（s）/m增加到17864 N（s）/m。壁弹性平均为77 N/m；这估计了力与稳态反应变化之间的关系。对照BNA反应也有快速和缓慢（重置）部分。BNA与壁反应关系（BNA/m）被定义为具有比例和动态成分的转导增益（T-G）。在亚组中，蛋白酶处理消除了壁蠕变和压力感受器重置，提示存在一种影响窦平滑肌的内皮介质。组织学数据表明酶损伤仅限于内膜组织，且硝苯地平未阻断神经结构上的Ca2+通道。通过比较处理前后的反应，T-G的比例成分等同于弹性影响（1/E），其中E = 7.5×10^(-6) m/BNA，而动态成分等同于粘性影响（1/V），其中V = 1.53×10^(-4) m（s）/BNA。通过BNA/m = 1/(Vs + E)（一阶传递函数）估计了压力感受器 - 组织联系的一个简单但基本的关系。
