Date on Master's Thesis/Doctoral Dissertation

12-2016

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Anatomical Sciences and Neurobiology

Degree Program

Anatomical Sciences and Neurobiology, PhD

Committee Chair

Magnuson, David

Committee Co-Chair (if applicable)

Benton, Richard

Committee Member

Benton, Richard

Committee Member

Hoying, James

Committee Member

Ovechkin, Alexander

Committee Member

Petruska, Jeffrey

Author's Keywords

spinal cord injury; cardiovascular; exercise rehabilitation; blood pressure; autonomic dysreflexia; autonomic nervous system dysfunction

Abstract

Spinal cord injury (SCI) results in whole-body dysfunction. While the majority of SCI research is focused on improving locomotor function after injury, cardiovascular (CV) disease continues to be the leading cause of morbidity in the chronic SCI patient population. The combination of injury-induced destruction of autonomic pathways, maladaptive plasticity within lumbosacral circuits, and the progressive decline in physical fitness contribute to the poor CV status of SCI individuals. Currently, there is little emphasis on implementing appropriately-timed acute rehabilitation techniques aimed to curtail maladaptive remodeling and improve CV outcomes. Furthermore, no pre-clinical or clinical studies have investigated the most appropriate time-course for exercise implementation or directly compared the CV effects of various exercise modalities. Most clinical studies examine the benefits of exercise in the chronic SCI population, a time by which the effects of maladaptive plasticity in autonomic circuitry may already be impacting CV control. We hypothesize that acute rehabilitation implementation will protect against maladaptive autonomic remodeling, improve CV control and function, and result in cardio-metabolic protective effects post-SCI. The work presented in this dissertation focuses on elucidating the physiological mechanisms responsible for maintaining CV control following a clinically-relevant model of incomplete SCI. A combination of echocardiography and blood pressure telemetry was used to assess CV control and function during rest and exercise challenge, and following acutely-implemented exercise-associated rehabilitation in SCI rodents. Incomplete SCI resulted in austere CV dysfunction, most notably during exercise challenge. Further, neither acutely-implemented passive hind-limb cycling nor active swimming rehabilitation attenuated the lack of CV control.