el-Bohy A A, Schrimsher G W, Reier P J, Goshgarian H G
Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan 48201, USA.
Exp Neurol. 1998 Mar;150(1):143-52. doi: 10.1006/exnr.1997.6757.
In this study, we describe a new method for quantitative assessment of phrenic inspiratory motor activity in two models of cervical spinal cord contusion injury. Anesthetized rats received contusion injury either to the descending bulbospinal respiratory pathway on one side of the spinal cord alone (C2 lateralized contusion) or to both the descending pathway, as well as the phrenic motoneuron pool bilaterally (C4/C5 midline contusion). Following injury, respiratory-associated phrenic nerve motor activity was recorded under standardized and then asphyxic conditions. Phrenic nerve efferent activity was rectified, integrated, and quantitated by determining the mean area under the integrated neurograms. The mean integrated area of the four inspiratory bursts recorded just before turning off the ventilator (to induce asphyxia) was determined and divided by the integrated area under the single largest respiratory burst recorded during asphyxia. This latter value was taken as the maximal inspiratory motor response that the rat was capable of generating during respiratory stress. Thus, a percentage of the maximal inspiratory motor drive was established for breathing in control and injured rats under standardized conditions. The results indicate that noninjured rats use 52 +/- 1.8% of maximal inspiratory motor drive under standardized conditions. In C2-contused rats, the results showed that while the percentage of maximal inspiratory motor drive on the noncontused side was similar to the control (55 +/- 4.1%), it was increased on the contused side (78 +/- 2.6%). In C4/5 lesions, the results indicate that this percentage was increased on both sides (77 +/- 4.4%). The results show the feasibility for performing quantitative evaluation of respiratory dysfunction in an animal model of cervical contusion injury. These findings lend to further development of this model for investigations of neuroplasticity and/or therapeutic interventions directed at ameliorating respiratory compromise following cervical spinal cord trauma.
在本研究中，我们描述了一种在两种颈脊髓挫伤损伤模型中定量评估膈神经吸气运动活性的新方法。麻醉的大鼠接受脊髓损伤，要么仅损伤脊髓一侧的下行延髓脊髓呼吸通路（C2侧方挫伤），要么同时损伤双侧的下行通路以及膈运动神经元池（C4/C5中线挫伤）。损伤后，在标准化条件下然后在窒息条件下记录与呼吸相关的膈神经运动活性。通过确定整合神经图下的平均面积，对膈神经传出活性进行整流、整合和定量。确定在关闭呼吸机（诱导窒息）前记录的四个吸气爆发的平均整合面积，并除以在窒息期间记录的单个最大呼吸爆发下的整合面积。后一个值被视为大鼠在呼吸应激期间能够产生的最大吸气运动反应。因此，在标准化条件下，为对照大鼠和受伤大鼠的呼吸建立了最大吸气运动驱动的百分比。结果表明，未受伤的大鼠在标准化条件下使用最大吸气运动驱动的52±1.8%。在C2挫伤的大鼠中，结果表明，虽然未挫伤侧的最大吸气运动驱动百分比与对照相似（55±4.1%），但在挫伤侧增加（78±2.6%）。在C4/5损伤中，结果表明两侧的该百分比均增加（77±4.4%）。结果显示了在颈挫伤损伤动物模型中对呼吸功能障碍进行定量评估的可行性。这些发现有助于进一步开发该模型，用于研究神经可塑性和/或针对改善颈脊髓损伤后呼吸功能不全的治疗干预措施。
