Studies of mammalian CSF dynamics have been focused on three things: paravascular flow, pressure and pulsatility, and “bulk” flow; and three (respective) potential motive forces have been identified: vasomotor, cardiac, and ventilatory. There are unresolved questions in each area, and few links between the different areas. The American alligator (Alligator mississippiensis) has pronounced plasticity in its ventilatory and cardiovascular systems. This study was designed to test the hypothesis that the greater cardiovascular and ventilatory plasticity of A. mississippiensis would result in more variation within the CSF dynamics of this species. Pressure transducers were surgically implanted into the cranial subarachnoid space of 12 sub-adult alligators; CSF pressure and pulsatility were monitored along with EKG and the exhalatory gases. In four of the alligators a second pressure transducer was implanted into the spinal subarachnoid space. In five of the alligators the CSF was labeled with artificial microspheres and Doppler ultrasonography used to quantify aspects of the spinal CSF flow. Both temporal and frequency analyses of the CSF pulsations showed highly variable contributions of both the cardiac and ventilatory cycles. Unlike the mammalian condition, the CSF pressure pulsations in the alligator are often of long (~ 3 s) duration, and similar duration CSF unidirectional flow pulses were recorded along the spinal cord. Reduction of the duration of the CSF pulsations, as during tachycardia, can lead to a “summation” of the pulsations. There appears to be a minimum duration (~ 1 s) of isolated CSF pulsations. Simultaneous recordings of cranial and spinal CSF pressures reveal a 200 ms delay in the propagation of the pressure pulse from the cranium to the vertebral canal. Most of the CSF flow dynamics recorded from the alligators, are similar to what has been reported from studies of the human CSF. It is hypothesized that the link between ventilatory mechanics and CSF pulsations in the alligator is mediated by displacement of the spinal dura. The results of the study suggest that understanding the CSF dynamics of Alligator may provide unique insights into the evolutionary origins and functional regulation of the human CSF dynamics.

中文翻译：

---

美国短吻鳄（Alligator Mississippiensis）脑脊液动力学的变化

哺乳动物脑脊液动力学的研究集中在三件事上：血管旁血流、压力和搏动，以及“体”流；并且已经确定了三种（各自的）潜在动力：血管舒缩动力、心脏动力和通气动力。每个领域都有未解决的问题，不同领域之间的联系很少。美洲短吻鳄 (Alligator Mississippiensis) 的呼吸系统和心血管系统具有明显的可塑性。本研究旨在检验以下假设：密西西比拟南芥更大的心血管和通气可塑性会导致该物种的脑脊液动力学发生更多变化。压力传感器通过手术植入12只亚成年鳄鱼的颅蛛网膜下腔；CSF 压力和搏动与心电图和呼出气体一起监测。在其中四只鳄鱼中，第二个压力传感器被植入脊髓蛛网膜下腔。其中五只鳄鱼的脑脊液用人工微球标记，多普勒超声用于量化脊髓脑脊液流动的各个方面。脑脊液脉动的时间和频率分析都显示心脏和通气周期的高度可变的贡献。与哺乳动物不同，鳄鱼的脑脊液压力脉动通常持续很长时间（~3 秒），并且沿着脊髓记录到类似持续时间的脑脊液单向流动脉冲。减少 CSF 脉动的持续时间，如在心动过速期间，可导致脉动的“总和”。孤立的 CSF 脉动似乎有最短持续时间 (~ 1 s)。同时记录颅骨和脊髓 CSF 压力显示压力脉冲从颅骨到椎管的传播延迟了 200 毫秒。从鳄鱼记录的大多数脑脊液流动动力学与人类脑脊液研究报告的类似。据推测，鳄鱼的呼吸力学和脑脊液搏动之间的联系是由脊髓硬脑膜的位移介导的。研究结果表明，了解鳄鱼的脑脊液动力学可能为人类脑脊液动力学的进化起源和功能调节提供独特的见解。据推测，鳄鱼的呼吸力学和脑脊液搏动之间的联系是由脊髓硬脑膜的位移介导的。研究结果表明，了解鳄鱼的脑脊液动力学可能为人类脑脊液动力学的进化起源和功能调节提供独特的见解。据推测，鳄鱼的呼吸力学和脑脊液搏动之间的联系是由脊髓硬脑膜的位移介导的。研究结果表明，了解鳄鱼的脑脊液动力学可能为人类脑脊液动力学的进化起源和功能调节提供独特的见解。