Cardiac and skeletal muscle mitochondria have a monocarboxylate transporter MCT1.
Level 5 - mechanism / opinion, no new human data
Bench and animal tissue laboratory study without human clinical data.
PubMed 10562613 · doi:10.1152/jappl.1999.87.5.1713
What was done
Researchers isolated subsarcolemmal and interfibrillar mitochondria from rat cardiac and skeletal muscle to evaluate the presence of monocarboxylate transporter-1 (MCT1). They probed isolated mitochondrial fractions and sarcolemmal membranes using Western blotting with antibodies to MCT1, evaluated potential membrane cross-contamination using the sarcolemmal marker GLUT-1, and verified localization in situ using immunolabeling and electron microscopy.
What was found
Western blotting confirmed the presence of MCT1 in sarcolemmal membranes and in both subsarcolemmal and interfibrillar mitochondria, with minimal cell membrane contamination as indicated by GLUT-1 probing. In situ immunolabeling and electron microscopy similarly demonstrated mitochondrial MCT1 localization. The abstract reports no numerical values, concentrations, or statistical metrics.
Why it matters
This study provides structural evidence that striated muscle mitochondria contain MCT1, supporting the cellular mechanism for mitochondrial lactate oxidation and the intracellular lactate shuttle hypothesis.
Limits
This was an animal tissue bench study in rats without human clinical validation. The abstract does not report the sample size (number of animals or technical replicates), quantitative transport kinetics, or functional oxidation rates.
Cited by
- supports Lactate transporters are located in plasma membranes and within the mitochondrial reticulum as lactate/pyruvate transporters.