Effect of forty-eight-hour glucose infusion into rats on islet ion fluxes, ATP/ADP ratio and redox ratios of pyridine nucleotides
| Autor: | Ayman A. Ahmed, M. Bacher, M. Roenfeldt, W. F. Brändle, M. A. Wahl, Hermann P. T. Ammon, A. Waheed, M. E. El-Sayed |
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| Rok vydání: | 1998 |
| Předmět: |
medicine.medical_specialty
Endocrinology Diabetes and Metabolism medicine.medical_treatment chemistry.chemical_element Calcium Carbohydrate metabolism Biology Islets of Langerhans chemistry.chemical_compound Adenosine Triphosphate Endocrinology Internal medicine Insulin Secretion medicine Animals Insulin Rats Wistar Pancreatic hormone Pancreatic islets Metabolism NAD Rats Adenosine Diphosphate Glucose medicine.anatomical_structure L-Glucose chemistry Basal (medicine) Female Oxidation-Reduction Rubidium Radioisotopes NADP |
| Zdroj: | Journal of Endocrinology. 156:583-590 |
| ISSN: | 1479-6805 0022-0795 |
| Popis: | Glucose infusion into rats has been shown to sensitize/desensitize insulin secretion in response to glucose. In pancreatic islets from glucose-infused rats (GIR) (48 h, 50%, 2 ml/h) basal insulin release (2.8 mmol/l glucose) was more than fourfold compared with islets from saline-infused controls and the concentration-response curve for glucose was shifted to the left with a maximum at 11.1 mmol/l. The concentration-response curve for 45Ca2+ uptake was also shifted to the left in islets from GIR with a maximum at 11.1 mmol/l glucose. Starting from a high basal level at 2.8 mmol/l glucose KCl produced no insulin release or 45Ca2+ uptake in islets from GIR. Islets from GIR exhibited a higher ATP/ADP ratio in the presence of 2.8 mmol/l glucose and marked inhibition of 86Rb+ efflux occurred even at 3 mmol/l glucose. Moreover, in islets from GIR the redox ratios of pyridine nucleotides were increased. On the other hand insulin content was reduced to about 20%. The data suggest that a 48-h glucose infusion sensitizes glucose-induced insulin release in vitro in concentrations below 11.1 mmol/l. This may, at least in part, be due to enhanced glucose metabolism providing increased availability of critical metabolic factors including ATP which, in turn, decrease the threshold for depolarization and therefore calcium uptake. Calcium uptake may then be further augmented by elevation of the redox state of pyridine nucleotides. |
| Databáze: | OpenAIRE |
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