Properties of isolated human islets of Langerhans: insulin secretion, glucose oxidation and protein phosphorylation
| Autor: | D. E. Harrison, Michael R. Christie, D. W. R. Gray |
|---|---|
| Rok vydání: | 1985 |
| Předmět: |
Adult
Male endocrine system medicine.medical_specialty Myosin light-chain kinase endocrine system diseases Endocrinology Diabetes and Metabolism medicine.medical_treatment Biology Carbohydrate metabolism Islets of Langerhans Calmodulin Internal medicine Insulin Secretion Internal Medicine medicine Humans Insulin Protein phosphorylation Kinase activity Phosphorylation Protein kinase A Proteins Metabolism Middle Aged Endocrinology Glucose Blood sugar regulation Calcium Electrophoresis Polyacrylamide Gel Female Oxidation-Reduction |
| Zdroj: | Diabetologia. 28(2) |
| ISSN: | 0012-186X |
| Popis: | In the present study, human islets were isolated by collagenase digestion from the pancreases of three kidney donors. Maintainance of the islets in tissue culture enabled insulin release, glucose oxidation and Ca2+ -calmodulin-dependent protein phosphorylation to be determined using the same islets. Increasing glucose over a range 0-20 mmol/l resulted in a sigmoidal stimulation of insulin release (28.8 +/- 5.2 to 118.4 +/- 25.8 microU . islet-1 . h-1, n = 10; threshold less than 4 mmol/l). There was a marked correlation between the insulin secretory response of the islets to glucose and their rate of glucose oxidation (5.9 +/- 0.3 at glucose 2 mmol/l up to 25.8 +/- 1.8 pmol . islet-1 . h-1 at 20 mmol/l, r = 0.98). N-acetylglucosamine (20 mmol/l) failed to elicit a secretory response from the islets. Stimulation of insulin secretion by glucose was dependent upon the presence of extracellular Ca2+. Extracts of the islets contained a Ca2+ -calmodulin-dependent protein kinase which phosphorylated a 48-kdalton endogenous polypeptide. Myosin light-chain kinase activity was demonstrated in the presence of exogenous myosin light chains. This report demonstrates for the first time the sigmoidal nature of glucose-stimulated insulin release from isolated human islets, and its correlation with enhanced glucose oxidation. Furthermore, this is the first report of the presence of Ca2+ -dependent protein kinases in human islets. |
| Databáze: | OpenAIRE |
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