Effects of acute hyperinsulinemia on skeletal muscle mitochondrial function, reactive oxygen species production, and metabolism in premenopausal women

Abstract

Background Acute metabolic demands that promote excessive and/or prolonged reactive oxygen species production may stimulate changes in mitochondrial oxidative capacity. Purpose To assess changes in skeletal muscle H2O2 production, mitochondrial function, and expression of genes at the mRNA and protein levels regulating energy metabolism and mitochondrial dynamics following a hyperinsulinemic-euglycemic clamp in a cohort of 11 healthy premenopausal women Methods Skeletal muscle biopsies of the vastus lateralis were taken at baseline and immediately following the conclusion of a hyperinsulinemic-euglycemic clamp. Mitochondrial production of H2O2 was quantified fluorometrically and mitochondrial oxidation supported by pyruvate, malate, and succinate (PMS) or palmitoyl carnitine and malate (PCM) was measured by high-resolution respirometry in permeabilized muscle fiber bundles. mRNA and protein levels were assessed by real time PCR and Western blotting. Results H2O2 emission increased following the clamp (P<0.05). Coupled respiration (State 3) supported by PMS and the respiratory control ratio (index of mitochondrial coupling) for both PMS and PCM were lower following the clamp (P<0.05). IRS1 mRNA decreased, whereas PGC1α and GLUT4 mRNA increased following the clamp (P≤0.05). PGC1α, IRS1, and phosphorylated AKT protein levels were higher after the clamp compared to baseline (P<0.05). Conclusions This study demonstrated that acute hyperinsulinemia induced H2O2 production and a concurrent decrease in coupling of mitochondrial respiration with ATP production in a cohort of healthy premenopausal women. Future studies should determine if this uncoupling ameliorates peripheral oxidative damage, and if this mechanism is impaired in diseases associated with chronic oxidative stress.

Skeletal muscle mitochondrial network dynamics in metabolic disorders and aging

“…Similarly, in humans MFN2 mRNA correlated with glucose oxidation and increases in mRNA levels following bariatric surgery were positively correlated with the percentage change in glucose oxidation between fasted and insulin-stimulated conditions during a hyperinsulinemic-euglycemic clamp procedure [40]. In healthy premenopausal women, MFN2 protein expression was associated with ROS-emitting capacity in permeabilized skeletal muscle fibers [44]. Expression of the inner mitochondrial membrane fusion protein optic atrophy-1 (OPA1), along with the mitochondrial fission protein FIS1, was highest in athletes compared with individuals with T2D [45].…”

Adenosine Triphosphate Production of Muscle Mitochondria after Acute Exercise in Lean and Obese Humans

“…Mitochondrial function has been linked to insulin sensitivity (35), and available evidence indicates that individuals that respond to exercise training with increased ATP synthesis show enhanced insulin sensitivity (36). We did not assess insulin sensitivity directly using the hyperinsulinemic-euglycemic clamp, as such experimental manipulation alters the mitochondrial function (37). Yet, when compared to the hyperinsulinemic-euglycemic clamp, QUICKI, measured under steady-state plasma glucose and insulin concentrations, provides reliable estimates of insulin sensitivity in peripheral tissues (19).…”

The Ryanodine Receptor as a Sensor for Cellular Environments in Muscles

“…Decreased glucose utilization and increased β-oxidation increase ROS, as does the consumption of a high-fat diet. The production of H2O2 is increased 1.5 times in hyperinsulinemic premenopausal women [152]. When ROS scavengers and CaMKII inhibitors were added to the myocardium from diabetic models, the peak Ca 2+ transients were normalized and spontaneous Ca 2+ release was suppressed [151][153].…”