Isolation of mitochondrial subpopulations from skeletal muscle: Optimizing recovery and preserving integrity.
Level 5 - mechanism / opinion, no new human data
Bench and animal methodological research with no human clinical data.
PubMed 30168663 · doi:10.1111/apha.13182
What was done
The authors modified existing protocols for isolating subsarcolemmal (SSM) and interfibrillar (IFM) mitochondrial subpopulations from rat skeletal muscle. Modifications included decreasing dispase concentration and homogenization speed, adding trypsin treatment to SSM fractions, and performing low-speed recentrifugation to remove subcellular debris. Isolation efficiency, organelle morphology, functional recovery, and membrane integrity were evaluated using light and electron microscopy alongside mitochondrial respiration and enzyme activity assays.
What was found
The modified protocol yielded an 80% recovery of total mitochondria from the initial muscle tissue. Both SSM and IFM fractions demonstrated <1% inner membrane damage, 8% outer membrane damage, and a respiratory control ratio of 16. A 10% difference in oxidative capacity between SSM and IFM using complex-I substrate was statistically significant only in the presence of saturating ADP concentrations.
Why it matters
Investigating distinct functional pools of skeletal muscle mitochondria has been hindered by low yields and disruption of mitochondrial integrity. This optimized method provides a reproducible protocol to recover high proportions of functional, intact mitochondrial subpopulations for metabolic and physiological research.
Limits
The study was conducted entirely on rat skeletal muscle, and generalizability to human muscle biopsies or other tissues was not assessed. The abstract does not report the number of animals or biological replicates utilized, nor does it provide baseline recovery percentages from conventional isolation methods for direct statistical comparison.
Cited by
- supports Subsarcolemmal and interfibrillar mitochondria in skeletal muscle have different proteomic compositions, morphologies, rates of ATP synthesis, ROS production, and calcium handling capacities.