Summary
Glucose and fatty acid oxidation has been measured in normal guinea-pig islets of Langerhans, and in A2-cell rich islets from streptozotocin-treated guinea-pigs. The rate of oxidation of these compounds in guinea-pig A2-cells and B-cells has been estimated. In the B-cells, the oxidation of glucose and octanoic acid responded markedly to changes in the extracellular levels of these substrates. Palmitic acid did not appear to be oxidized by the B-cells. In contrast, the oxidation of octanoic acid and palmitic acid in the A2-cells was very sensitive to changes in the extracellular fatty acid concentration. The sensitivity of glucose oxidation to changes in the glucose concentration was small by comparison. The high rate of oxidation of fatty acids in the A2-cells supports the view that the rate of fatty acid metabolism in these cells plays an important role in the regulation of glucagon release.
Résumé
L'oxydation du glucose et des acides gras a été mesurée dans les îlots normaux de Langerhans chez le cobaye, ainsi que dans les îlots riches en cellules A2 du cobaye traité à la streptozotocine. Le taux d'oxydation de ces composés dans les cellules A2 et les cellules B du cobaye a été estimé. Dans les cellules B, l'oxydation du glucose et de l'acide octanoique a fortement répondu à des changements dans les taux extra-cellulaires de ces substrats. L'acide palmitique ne semble pas avoir été oxydé par les cellules B. Au contraire, l'oxydation de l'acide octanoique et de l'acide palmitique dans les cellules A2 était très sensible aux changements dans la concentration des acides gras extra-cellulaires. La sensibilité de l'oxydation du glucose envers les changements dans la concentration du glucose était comparativement faible. Le taux élevé de l'oxydation des acides gras dans les cellules A2 corrobore l'hypothèse que le degré du métabolisme des acides gras dans ces cellules joue un rôle important dans la régulation de la sécrétion du glucagon.
Zusammenfassung
An normalen Langerhansschen Inseln vom Meerschweinchen und an mit A2-Zellen angereicherten Inseln von streptozotozin-behandelten Meerschweinchen wurde die Oxidation von Glucose und Fettsäuren gemessen und die Oxidationsrate in A2-Zellen und B-Zellen des Meerschweinchens bestimmt. In den B-Zellen hing die Oxidation von Glucose und Octansäure stark von den Änderungen der extracellulären Konzentrationen dieser Substanzen ab. Palmitinsäure schien in den B-Zellen nicht oxidiert zu werden. Dagegen war die Oxidation von Oktansäure und Palmitinsäure in den A2-Zellen sehr von den Schwankungen der extracellulären Fettsäurekonzentration abhängig. Die Änderung der Glucoseoxidation bei Schwankungen der Glucosekonzentration war im Verhältnis dazu gering. Die hohe Oxidationsrate der Fettsäuren in den A2-Zellen unterstützt die Theorie, daß der Fettsäuremetabolismus dieser Zellen eine wesentliche Rolle in der Regulierung der Glucose-sekretion spielt.
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Edwards, J.C., Hellerström, C., Petersson, B. et al. Oxidation of glucose and fatty acids in normal and in A2-cell rich pancreatic islets isolated from guinea-pigs. Diabetologia 8, 93–98 (1972). https://doi.org/10.1007/BF01235632
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DOI: https://doi.org/10.1007/BF01235632