Abstract
Oxidative damage to the diaphragm as a result of cervical spinal cord injury (SCI) promotes muscle atrophy and weakness. Respiratory insufficiency is the leading cause of morbidity and mortality in cervical spinal cord injury (SCI) patients, emphasizing the need for strategies to maintain diaphragm function. Hyperbaric oxygen (HBO) increases the amount of oxygen dissolved into the blood, elevating the delivery of oxygen to skeletal muscle and reactive oxygen species (ROS) generation. It is proposed that enhanced ROS production due to HBO treatment stimulates adaptations to diaphragm oxidative capacity, resulting in overall reductions in oxidative stress and inflammation. Therefore, we tested the hypothesis that exposure to HBO therapy acutely following SCI would reduce oxidative damage to the diaphragm muscle, preserving muscle fiber size and contractility. Our results demonstrated that lateral contusion injury at C3/4 results in a significant reduction in diaphragm muscle-specific force production and fiber cross-sectional area, which was associated with augmented mitochondrial hydrogen peroxide emission and a reduced mitochondrial respiratory control ratio. In contrast, rats that underwent SCI followed by HBO exposure consisting of 1 h of 100% oxygen at 3 atmospheres absolute (ATA) delivered for 10 consecutive days demonstrated an improvement in diaphragm-specific force production, and an attenuation of fiber atrophy, mitochondrial dysfunction and ROS production. These beneficial adaptations in the diaphragm were related to HBO-induced increases in antioxidant capacity and a reduction in atrogene expression. These findings suggest that HBO therapy may be an effective adjunctive therapy to promote respiratory health following cervical SCI.
Highlights
Cervical spinal cord injury (SCI) compromises respiratory function as a result of damage to respiratory neural circuitry required for diaphragm muscle contraction [1]
No differences in body weight existed between groups prior to the initiation of the experimental protocol non-injured, room air exposure (CON) = 240.1 ± 2.7 g; lateral-cervical spinal cord contusion (SCI) = 230.8 ± 4.3 g; lateral-cervical spinal cord contusion, Hyperbaric oxygen (HBO) therapy (SCI + HBOT) = 232.0 ± 2.9 g)
At stimulation frequencies of 60–160 Hz, diaphragm muscle force production from the SCI + HBOT group remained significantly elevated compared to the SCI group, but specific force was depressed compared to the CON group
Summary
Cervical spinal cord injury (SCI) compromises respiratory function as a result of damage to respiratory neural circuitry required for diaphragm muscle contraction [1]. Following cervical SCI, the development of diaphragm dysfunction increases the risk of respiratory complications, morbidity and mortality as a result of atelectasis, pneumonia and ventilator dependence [3]. Preserving diaphragm muscle health by mitigating atrophy and improving contractility should facilitate respiratory rehabilitation and positive respiratory outcomes after cervical SCI. Administration of the antioxidant Trolox immediately following SCI mitigates much of the diaphragm weakness while reducing mitochondrial and oxidative damage [5].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
