Postabsorptive respiratory quotient and insulin-stimulated glucose storage rate in nondiabetic pima indians are related To glycogen synthase fractional activity in cultured myoblasts.
AUTOR(ES)
Mott, D M
RESUMO
A decreased ratio of fat to carbohydrate oxidation rate (an elevated respiratory quotient) predicts the development of obesity. Skeletal muscle accounts for a major fraction of total body lipid oxidation and is the principle site for reduced glucose storage in insulin-resistant subjects. The potentially important role that muscle has in promoting obesity or insulin resistance may be based on metabolic control intrinsic to skeletal muscle. Cultured skeletal muscle provides a system to examine the importance of inherent metabolic traits in muscle biopsies from obese and insulin-resistant subjects. Glycogen synthase fractional activity (GSFA) was measured in cultured myoblasts from 21 Pima Indians characterized in vivo using indirect calorimetry and a euglycemic hyperinsulinemic clamp. Basal GSFA in cultured muscle cells is inversely correlated with postabsorptive respiratory quotient of the muscle donors (r = -0.66, P = 0.001) and with in vivo high dose insulin-stimulated glucose storage rates (r = 0.47, P = 0.04). These results indicate that the postabsorptive respiratory quotients and insulin-mediated glucose storage rates in vivo share a common regulatory mechanism with GSFA in cultured myoblasts. Abnormal regulation of glycogen synthase phosphorylation state may be an intrinsic defect in skeletal muscle associated with obesity and insulin resistance.
ACESSO AO ARTIGO
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