Fasting Decreases the Content of D-Chiroinositol in Human Skeletal Muscle |
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Authors: | Pavel N Shashkin Laura C Huang Joseph Larner George E Vandenhoff Abram Katz |
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Institution: | 1. Department of Internal Medicine, University of Virginia Charlottesville, Charlottesville, Virginia, USA.;2. Department of Pharmacology, University of Virginia Charlottesville, Charlottesville, Virginia, USA.;3. Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, 171 77 , Sweden, |
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Abstract: | Two classes of inositol phosphoglycans have been implicated as
second messengers of insulin, one that activates pyruvate dehydrogenase
and contains D-chiroinositol, and one that inhibits cyclic
AMP–dependent protein kinase and contains myoinositol. We examined
the effects of a 3-day fast on muscle contents of inositols
in healthy humans. An oral glucose tolerance test was performed
and a biopsy was obtained from the quadriceps femoris muscle
after an overnight fast and after a 72-hour fast. The 72-hour fast
significantly increased plasma glucose (1.5- to 2-fold) and insulin
(2- to 4-fold) after glucose ingestion versus the values after the
overnight fast, indicating the manifestation of peripheral insulin
resistance. The 72-hour fast resulted in an ∼20% decrease in the
muscle content of D-chiroinositol (P < 0.02), but no change in the
myoinositol content. These data demonstrate that fasting specifically
decreases the muscle content of D-chiroinositol in human muscle
and this may contribute to the finding that insulin-mediated activation
of pyruvate dehydrogenase is attenuated after short-term
starvation. |
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