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D-[1-14C]mannoheptulose uptake by the perfused pancreas of control and streptozotocin-induced diabetic rats

par Ladrière, Laurence ;Leclercq Meyer, Viviane ;Malaisse, Willy
Référence Diabetes research, 35, 3, page (103-116)
Publication Publié, 2000

Article révisé par les pairs

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Résumé :

D-[1-14C]mannoheptulose(0.1mM) was administered together with 3HOH for 20min in the isolated perfused pancreas from fed control rats, fasted control rats and streptozotocin-induced diabetic rats treated with insulin. The pancreases were then perfused for 10min with a non-radioactive medium and the pancreas examined for its radioactive content. Cytochalasin B (20μM) was administered for the last 15min of the experiments i.e. for 5min before and for 10min during circulation of the non-radioactive medium, in order to prevent the efflux of D-[1-14C]mannoheptulose from labelled cells during the wash out of extracellular radioactivity. In all cases, the fractional turnover rate of radioactive material in the pancreatic parenchyma, as judged from the changes in effluent radioactivity at the onset or end of D-[1-14C]mannoheptulose and 3HOH administration, yielded higher values in the case of 14C outflow than 3H outflow. The paired difference between the 14C and 3H turnover rates averaged 0.140 ± 0.017min-1 (n=18). The paired ratio in the final 14C/3H radioactive content, both expressed as μl/mg wet weight by reference to the effluent radioactivity at min 60, averaged 0.944 ± 0.060 (n=18). None of these values were significantly different when comparing fed and starved control animals and STZ rats. Assuming that the 14C-labelled heptose used in these experiments corresponds to true D-[1-14C]mannoheptulose, these negative findings indicate that the present experimental design is not suitable to assess the relative contribution of B-cells to the overall mass of the pancreatic gland.