Abstract:
This thesis investigated whole body glucose disposal and the adaptive changes in
skeletal muscle carbohydrate metabolism following 28 d of supplementation with 1000
mg R(+)-lipoic acid in young sedentary males (age, 22.1 ± 0.67 yr, body mass, 78.7 ±
10.3 kg, n=9). In certain individuals, lipoic acid decreased the 180-min area under the
glucose concentration and insulin concentration curve during an oral glucose tolerance
test (OGTT) (n=4). In the same individuals, lipoic acid supplementation decreased
pyruvate dehydrogenase kinase activity (PDK) (0.09 ± 0.024 min"^ vs. 0.137 ± 0.023
min'\ n=4). The fasting levels of the activated form of pyruvate dehydrogenase (PDHa)
were decreased following lipoic acid (0.42 ± 0.13 mmol-min'kg'^ vs. 0.82 ± 0.32
mmolrnin'^kg"\ n=4), yet increased to a greater extent during the OGTT (1.21 ± 0.34
mmol-min'kg"' vs. 0.81 ±0.13 mmolmin"'kg'\ n=4) following hpoic acid
supplementation. No changes were demonstrated in the remaining subjects (n=5). It was
concluded that improved glucose clearance during an OGTT following lipoic acid
supplementation is assisted by increased muscle glucose oxidation through increased
PDHa activation and decreased PDK activity in certain individuals.
