<em>In Vivo</em> Telemetry to Record Long-Term Cardiovascular Parameters, Temperature, and Activity in Spinal Cord Injury Rat Models

Higher-level spinal cord injury (SCI) above thoracic level 6 (T6) disrupts autonomic function and contributes to secondary complications, including fluctuations in blood pressure, heart rate, and temperature. In rats, the placement of telemetric implants in the descending aorta offers a robust methodology for assessing various cardiovascular parameters, such as systolic and diastolic pressure, mean arterial pressure, and heart rate. Core body temperature and animal activity can also be recorded following telemetric implant placement. A rat with a telemetric implant is kept on the receiver plate connected to a computer system for recording various parameters. Continuous long-term recordings at defined time intervals allow for the quantification of injury-induced physiological disruptions, including day-night variations in cardiovascular function. Comparing pre-injury (baseline) and post-injury recordings enables researchers to assess the impact of SCI on these physiological metrics. This methodology paper outlines a detailed, step-by-step procedure for telemetric implant placement in the descending aorta (using mono-occlusion of the artery) of the rat, as well as continuous telemetry recording following severe-high thoracic (T3) SCI. We discuss the challenges typically encountered while performing this procedure, as well as a dedicated troubleshooting section. The data acquisition process using Ponemah software and its various applications are also discussed. Rats display SCI-associated cardiovascular, temperature, and activity abnormalities, and telemetric implants are effective devices for studying these post-injury complications and evaluating potential treatments.