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Free radical-induced contractile protein dysfunction in endotoxin-induced sepsis
L A Callahan1, D Nethery, D Stofan
1Pulmonary Division, Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.
American Journal of Respiratory Cell and Molecular Biology
|February 13, 2001
Summary
Sepsis-induced free radicals damage skeletal muscle by altering contractile proteins. Scavenging superoxide and inhibiting nitric oxide synthase protects muscle force generation and prevents protein loss.
Area of Science:
- Biochemistry
- Physiology
- Pathology
Background:
- Sepsis is linked to increased free radicals like nitric oxide (NO) and superoxide in skeletal muscle.
- This free radical overproduction reduces muscle force, but the exact mechanism remains unclear.
Purpose of the Study:
- To investigate if free radicals directly damage contractile proteins in sepsis.
- To determine the role of superoxide and NO in sepsis-induced muscle dysfunction.
Main Methods:
- Compared force generation in Triton-skinned diaphragmatic fibers from control and endotoxin-treated rats.
- Administered superoxide scavenger (PEG-SOD) and NO synthase inhibitor (L-NAME) to endotoxin-treated rats.
- Analyzed protein content in muscle fibers using SDS-PAGE.
Main Results:
- Endotoxin reduced muscle fiber force-generating capacity (Fmax) and calcium sensitivity (Ca50).
- L-NAME and PEG-SOD prevented these reductions in endotoxin-treated rats.
- Endotoxin caused selective protein depletion, which L-NAME and PEG-SOD also prevented.
Conclusions:
- Free radicals (superoxide, NO) are central to altering skeletal muscle contractile protein function in endotoxin-induced sepsis.
- Targeting these free radicals may preserve muscle function during sepsis.