Sex and race contribute to variation in mitochondrial function and insulin sensitivity. Issue 19 (4th October 2021)

• Record Type: Journal Article
• Authors: Fisher, Gordon; Tay, Jeannie; Warren, Jonathan L.; Garvey, W. Timothy; Yarar‐Fisher, Ceren; Gower, Barbara A.
• Is Part Of: Physiological reports. Volume 9:Issue 19(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-04
• Subjects: insulin sensitivity -- mitochondrial function -- race -- reactive oxygen species -- sex; Physiology -- Periodicals; 571
• DOI: 10.14814/phy2.15049
• Languages: English
• ISSNs: 2051-817X

Abstract

Abstract: 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 H2 O2 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 (SIClamp ) using a euglycemic clamp at 120 mU/m 2 /min, muscle mitochondrial function using high‐resolution respirometry, H2 O2 emission using amplex red, and % myofiber composition. Results: SIClamp 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 H2 O2 production did not differ with race. Mitochondrial function was positively associated with insulin sensitivity in women but not men. Statistical adjustment for mitochondrial function, H2 O2 production, or fiber composition did not eliminate the race difference in SIClamp . Conclusion: Neither mitochondrial respiratory rates, coupling efficiency, myofiber composition, nor mitochondrial reactive oxygen species production explained lower SIClamp 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. Abstract : Present results do not support a role for mitochondrial function or fiber type in determining lower insulin sensitivity in African Americans. The source of lower skeletal‐muscle insulin sensitivity in African Americans remains unclear. Future research could focus on aspects of skeletal muscle composition, such as lipid species, and their association with insulin sensitivity in African Americans.