Effects of HBO2 on skeletal muscle calcium regulation and mitochondrial function
Abstract
Oxidants are increased during skeletal muscle contraction and are reported to contribute to fatigue. This may occur by oxidant activation of the sarcoplasm reticulum (SR) ryanodine receptor type 1 (RyR1) and SR calcium sensor stromal interacting molecule 1 (STIM1), resulting in excess mitochondrial calcium influx and impaired respiration and ATP production. Because hyperbaric oxygen (HBO2) increases the partial pressure of oxygen, it is plausible that oxidant production exceeds antioxidant defense mechanism and leads to dysregulated calcium handling and mitochondrial function. Our objective is, therefore, to determine the impact of skeletal muscle oxidant production on calcium regulation and mitochondrial function in mice exposed to HBO2. Our central hypothesis is that prolonged and repeated HBO2 exposures increases oxidation of RyR1 and STIM1 that increases intracellular and mitochondrial calcium uptake resulting in impaired mitochondrial function. The rationale is that it will determine if critical targets involved in muscle contraction are influenced by HBO2, and offer a strong scientific framework for testing specific drugs or antioxidants on muscle and aerobic exercise performance after HBO2. To test our hypothesis and attain our objective, the following three specific aims will be pursued by exposing C57BL/6 mice to three sessions of HBO2 at 2.5 atmospheres absolute or air for 6 h: 1) Measure skeletal muscle oxidant production after HBO2. 2) Measure skeletal muscle oxidation of RyR1 and STIM1, and calcium responses to HBO2. 3) Measure skeletal muscle mitochondrial membrane potential (m) and cellular energy state after HBO2. Following the third HBO2 exposure, the flexor digitorum brevis muscles will be harvested and isolated for real-time measurement of superoxide production, calcium flux and m using dyes and fluorescence microscopy. Immunoprecipitation and immunoblotting, and immunofluorescence methods will be used to measure oxidation of RyR1 and STIM1. The proposed research is significant because it will identify whether prolonged and repeated HBO2 exposures causes a defect in calcium handling and or mitochondrial function. The proximate expected outcomes of this work is knowledge of how HBO2 may be impacting components of muscular contraction that are contributing to muscular fatigue and early termination of aerobic activity. The results will have an important positive impact immediately because they will establish which pharmacological or antioxidant preventive approaches should be tested. The proposed research is relevant o warfighters because breathing 100% oxygen during diving operations can impair work performance and mitigation approaches are needed. This proposal addresses two of Undersea Medicine & Performance Concentration Areas: mitigation of hyperbaric oxygen toxicity and diver performance optimization.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 05, 2021
- Source ID
- N000142112279
Entities
People
- Heath G Gasier
Organizations
- Duke University
- Office of Naval Research
- United States Navy