Connelly C A, Ellenberger H H, Feldman J L
Department of Kinesiology, University of California, Los Angeles 90024-1568.
Am J Physiol. 1990 Feb;258(2 Pt 1):L33-44. doi: 10.1152/ajplung.1990.258.2.L33.
An anatomic projection from the retrotrapezoid nucleus to the ventral respiratory group in cat was previously reported by our laboratory (J. C. Smith, D. E. Morrison, H. H. Ellenberger, M. R. Otto, and J. L. Feldman. J. Comp. Neurol. 281: 69-96, 1989). We now report on the properties of neurons in the retrotrapezoid nucleus, investigated with extracellular recording techniques in 10 chloralose-urethane anesthetized, paralyzed, mechanically ventilated cats. A ventral exposure of the medulla facilitated recording from neurons in the retrotrapezoid nucleus, located ventral to the facial nucleus near the medullary surface. Respiratory-modulated, as well as irregularly discharging, spontaneous unit activity was recorded within the retrotrapezoid nucleus. Twelve respiratory-modulated units in the retrotrapezoid nucleus exhibited inspiratory (8 units), expiratory (3 units), or multimodal (1 unit) discharge patterns. Chemical activation of an inspiratory unit in the retrotrapezoid nucleus by pressure ejection of DL-homocysteic acid (less than 0.5 nl of 10 mM solution) demonstrated that the respiratory-modulated activity originated from the cell soma and not fibers of passage coursing through the retrotrapezoid nucleus region. Electrical microstimulation (20-40 microA, approximately 70-microseconds duration, biphasic pulse) within the ipsilateral ventral respiratory group elicited antidromic activation of 7 units in the retrotrapezoid nucleus, three of which were not spontaneously active. Electrical stimulation (5-80 microA, 70-microseconds pulse width, 100 Hz, 400- to 500-ms trains) at sites within retrotrapezoid nucleus affected the respiratory motor output when delivered during late expiration, eliciting premature onset of inspiration. These results suggest that retrotrapezoid nucleus projections to the ventral respiratory group (and dorsal respiratory group) may influence respiratory timing and pattern, perhaps by conveying signals originating in the rostral ventrolateral medulla that result from ventral surface perturbations.
我们实验室之前报道过猫的后梯形核向腹侧呼吸组的解剖投射（J. C. 史密斯、D. E. 莫里森、H. H. 埃伦伯格、M. R. 奥托和J. L. 费尔德曼。《比较神经学杂志》281: 69 - 96, 1989）。我们现在报告用细胞外记录技术对10只氯醛糖 - 乌拉坦麻醉、麻痹、机械通气的猫的后梯形核神经元特性进行的研究。延髓腹侧暴露便于记录位于延髓表面附近面神经核腹侧的后梯形核中的神经元。在后梯形核内记录到了呼吸调制以及不规则放电的自发单位活动。后梯形核中的12个呼吸调制单位表现出吸气（8个单位）、呼气（3个单位）或多模式（1个单位）放电模式。通过压力喷射DL - 高半胱氨酸（10 mM溶液小于0.5 nl）对后梯形核中的一个吸气单位进行化学激活表明，呼吸调制活动起源于细胞体而非穿过后梯形核区域的传入纤维。同侧腹侧呼吸组内的电微刺激（20 - 40微安，约70微秒持续时间，双相脉冲）引发了后梯形核中7个单位的逆向激活，其中3个单位无自发活动。在后梯形核内的位点进行电刺激（5 - 80微安，70微秒脉冲宽度，100赫兹，400 - 500毫秒串），在呼气末期施加时会影响呼吸运动输出，引发吸气提前开始。这些结果表明，后梯形核向腹侧呼吸组（和背侧呼吸组）的投射可能影响呼吸时间和模式，也许是通过传递源自延髓头端腹外侧因腹侧表面扰动而产生的信号。
