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Regulation of Carbohydrate Metabolism by 2,5-anhydro-D-mannitol

Patricio T. Riquelme, Mary Ellen Wernette-Hammond, Nancy M. Kneer and Henry A. Lardy
Proceedings of the National Academy of Sciences of the United States of America
Vol. 80, No. 14, [Part 1: Biological Sciences] (Jul. 15, 1983), pp. 4301-4305
Stable URL: http://www.jstor.org/stable/14014
Page Count: 5
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Regulation of Carbohydrate Metabolism by 2,5-anhydro-D-mannitol
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Abstract

In hepatocytes isolated from fasted rats, 2,5-anhydromannitol inhibits gluconeogenesis from lactate plus pyruvate and from substrates that enter the gluconeogenic pathway as triose phosphate. This fructose analog has no effect, however, on gluconeogenesis from xylitol, a substrate that enters the pathway primarily as fructose 6-phosphate. The sensitivity of gluconeogenesis to 2,5-anhydromannitol depends on the substrate metabolized; concentrations of 2,5-anhydromannitol required for 50% inhibition increase in the order lactate plus pyruvate < dihydroxyacetone < glycerol < sorbitol < fructose. The inhibition by 2,5-anhydromannitol of gluconeogenesis from dihydroxyacetone is accompanied by an increase in lactate formation and by two distinct crossovers in gluconeogenic-glycolytic metabolite patterns--i.e., increases in pyruvate concentrations with decreases in phosphoenolpyruvate and increases in fructose-1,6-bisphosphate concentrations with little change in fructose 6-phosphate. In addition, 2,5-anhydromannitol blocks the ability of glucagon to stimulate gluconeogenesis and inhibit lactate production from dihydroxyacetone. 2,5-Anhydromannitol decreases cellular fructose 2,6-bisphosphate content in hepatocytes; therefore the effects of the fructose analog are not mediated by fructose 2,6-bisphosphate, a naturally occurring allosteric regulator. 2,5-Anhydromannitol also inhibits gluconeogenesis in hepatocytes isolated from fasted diabetic rats, but higher concentrations of the analog are required.

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