Open AccessSex and race contribute to variation in mitochondrial function and insulin sensitivity
Author(s) -
Fisher Gordon,
Tay Jeannie,
Warren Jonathan L.,
Garvey W. Timothy,
YararFisher Ceren,
Gower Barbara A.
Publication year - 2021
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.15049
Subject(s) - medicine , insulin , endocrinology , biology , mitochondrion , glucose clamp technique , skeletal muscle , insulin sensitivity , insulin resistance , biochemistry
Objective Insulin sensitivity is lower in African American (AA) versus Caucasian American (CA). We tested the hypothesis that lower insulin sensitivity in AA could be explained by mitochondrial respiratory rates, coupling efficiency, myofiber composition, or H 2 O 2 emission. A secondary aim was to determine whether sex affected the results. Methods AA and CA men and women, 19–45 years, BMI 17–43 kg m 2 , were assessed for insulin sensitivity (SI Clamp ) using a euglycemic clamp at 120 mU/m 2 /min, muscle mitochondrial function using high‐resolution respirometry, H 2 O 2 emission using amplex red, and % myofiber composition. Results SI Clamp was greater in CA ( p < 0.01) and women ( p < 0.01). Proportion of type I myofibers was lower in AA ( p < 0.01). Mitochondrial respiratory rates, coupling efficiency, and H 2 O 2 production did not differ with race. Mitochondrial function was positively associated with insulin sensitivity in women but not men. Statistical adjustment for mitochondrial function, H 2 O 2 production, or fiber composition did not eliminate the race difference in SI Clamp . Conclusion Neither mitochondrial respiratory rates, coupling efficiency, myofiber composition, nor mitochondrial reactive oxygen species production explained lower SI Clamp in AA compared to CA. The source of lower insulin sensitivity in AA may be due to other aspects of skeletal muscle that have yet to be identified.