| Autor: |
Tamarit-Rodriguez, Jorge, Idahl, Lars-Ake, Gine, Elena, Alcazar, Oscar, Sehlin, Janove, Tamarit-Rodriguez, J, Idahl, L A, Giné, E, Alcazar, O, Sehlin, J |
| Předmět: |
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| Zdroj: |
Diabetes; Aug1998, Vol. 47 Issue 8, p1219-1223, 5p, 6 Graphs |
| Abstrakt: |
Lactate production, glucose utilization, glucose oxidation, and insulin release were studied in islets from rat and ob/ob mice. Lactate was determined with a highly sensitive method, based on esterification, subsequent separation, and quantitation with high-performance liquid chromatography. There was a significant lactate production in the absence of glucose, which increased with glucose concentrations up to 3 mmol/l, reaching its half-maximal rate in the presence of 0.2-1.0 mmol/l glucose in both species. Glucose utilization displayed a wider glucose concentration dependence, with a K0.5 value between 3 and 10 mmol/l glucose. The rates of glucose utilization and lactate production were similar at 3 mmol/l glucose in rat islets and at about 6 mmol/l glucose in ob/ob mice islets. Saturation of lactate production at low glucose concentrations is probably contributing to the observed preferential stimulation of oxidative metabolism at higher concentrations. D-Mannoheptulose caused a marked inhibition of glucose utilization and glucose oxidation at 20 mmol/l glucose in islets from rat or ob/ob mice, as would be expected from a competitive inhibition of glucokinase. By contrast, D-mannoheptulose reduced only marginally the islet metabolism at 3 mmol/l glucose, which is consistent with an effective mannoheptulose-induced inhibition of the glucokinase-dependent, minor part of glucose phosphorylation at this low glucose concentration. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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