Blood Pressure and Brain Blood Flow Regulation After Midodrine Administration in Those With Spinal Cord Injury

This project aims to evaluate the physiological effects of Midodrine administration during orthostatic challenge in those with high level spinal cord injury. Midodrine has been shown to improve orthostatic symptoms in those with spinal cord injury but the physiological mechanisms influenced have not been identified. The investigators will examine key physiological components influencing orthostatic tolerance. The investigators will do this, by measuring the baroreflex, and brain blood flow autoregulation (the ability to maintain brain blood flow) before during and after the sit-up test. Two sit-up tests will occur; one before Midodrine administration, and one after administration of a 10mg dose of Midodrine.