Department of Health & Sport Sciences, University of Louisville, Louisville, KY, USA.
Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.
Physiol Rep. 2021 Aug;9(15):e14969. doi: 10.14814/phy2.14969.
Hemodynamic instability and cardiovascular (CV) dysfunction are hallmarks of patients living with cervical and high thoracic spinal cord injuries (SCI). Individuals experience bouts of autonomic dysreflexia (AD) and persistent hypotension which hamper the activities of daily living. Despite the widespread use of exercise training to improve health and CV function after SCI, little is known about how different training modalities impact hemodynamic stability and severity of AD in a model of incomplete SCI. In this study, we used implantable telemetry devices to assess animals with T2 contusions following 3.5 weeks of exercise training initiated 8 days post-injury: passive hindlimb cycling (T2-CYC, n = 5) or active forelimb swimming (T2-SW, n = 6). Uninjured and non-exercised SCI control groups were also included (CON, n = 6; T2-CON, n = 7; T10-CON, n = 6). Five weeks post-injury, both T2-CON and T2-CYC presented with resting hypotension compared to uninjured CON and T10-CON groups; no differences were noted in resting blood pressure in T2-SW versus CON and T10-CON. Furthermore, pressor responses to colorectal distention (AD) were larger in all T2-injured groups compared to T10-CON, and were not attenuated by either form of exercise training. Interestingly, when T2-injured animals were re-stratified based on terminal BBB scores (regardless of training group), animals with limited hindlimb recovery (T2-LOW, n = 7) had more severe AD responses. Our results suggest that the spontaneous recovery of locomotor and autonomic function after severe but incomplete T2 SCI also influences the severity of AD, and that short periods (3.5 weeks) of passive hindlimb cycling or active forelimb swimming are ineffective in this model.
血流动力学不稳定和心血管（CV）功能障碍是患有颈胸段和高胸段脊髓损伤（SCI）患者的特征。患者会经历自主反射异常（AD）发作和持续性低血压，这会妨碍他们的日常生活活动。尽管广泛使用运动训练来改善 SCI 后的健康和 CV 功能，但对于不同的训练方式如何影响不完全 SCI 模型中的血流动力学稳定性和 AD 的严重程度知之甚少。在这项研究中，我们使用植入式遥测设备来评估 T2 挫伤后 3.5 周运动训练开始后 8 天的动物：被动后肢循环（T2-CYC，n=5）或主动前肢游泳（T2-SW，n=6）。未受伤和未进行运动训练的 SCI 对照组也包括在内（CON，n=6；T2-CON，n=7；T10-CON，n=6）。受伤后 5 周，与未受伤的 CON 和 T10-CON 组相比，T2-CON 和 T2-CYC 组的静息血压均较低；T2-SW 与 CON 和 T10-CON 组相比，静息血压无差异。此外，所有 T2 损伤组的结肠扩张（AD）加压反应均大于 T10-CON 组，并且两种运动训练方式均不能减轻加压反应。有趣的是，当根据终末 BBB 评分对 T2 损伤动物进行重新分层（无论训练组如何）时，后肢恢复有限的动物（T2-LOW，n=7）的 AD 反应更严重。我们的结果表明，严重但不完全的 T2 SCI 后运动和自主功能的自发恢复也会影响 AD 的严重程度，而短暂的（3.5 周）被动后肢循环或主动前肢游泳在这种模型中无效。
