Changes induced by sucrose administration on glucose metabolism in pancreatic islets in normal hamsters
We correlated the changes in glucose-induced insulin secretion with those observed in glucose metabolism and hexokinase/glucokinase activity in islets from normal sucrose-fed hamsters. Blood glucose and insulin levels were measured in normal male hamsters fed with (S5) or without (C5) 10% sucrose in...
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| Autores principales: | , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
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2001
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/84894 |
| Aporte de: |
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I19-R120-10915-84894 |
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| record_format |
dspace |
| institution |
Universidad Nacional de La Plata |
| institution_str |
I-19 |
| repository_str |
R-120 |
| collection |
SEDICI (UNLP) |
| language |
Inglés |
| topic |
Ciencias Médicas sucrose administration pancreatic islets β-cells |
| spellingShingle |
Ciencias Médicas sucrose administration pancreatic islets β-cells Massa, María Laura Borelli, María Inés Del Zotto, Héctor Herminio Gagliardino, Juan José Changes induced by sucrose administration on glucose metabolism in pancreatic islets in normal hamsters |
| topic_facet |
Ciencias Médicas sucrose administration pancreatic islets β-cells |
| description |
We correlated the changes in glucose-induced insulin secretion with those observed in glucose metabolism and hexokinase/glucokinase activity in islets from normal sucrose-fed hamsters. Blood glucose and insulin levels were measured in normal male hamsters fed with (S5) or without (C5) 10% sucrose in the drinking water for 5 weeks. Isolated islets (collagenase digestion) from both groups of animals were used to study insulin secretion, <SUP>14</SUP>CO<SUB>2</SUB> and <SUP>3</SUP>H<SUB>2</SUB>O production from D-[U-<SUP>14</SUP>C]-glucose and D-[5-<SUP>3</SUP>H]-glucose respectively, with 3.3 or 16.7 mM glucose in the medium, and hexokinase/glucokinase activity (fluorometric assay) in islet homogenates. Whereas S5 and C5 animals had comparable normal blood glucose levels, S5 showed higher insulin levels than C5 hamsters (2.3 ± 0.1 vs 0.6 ± 0.03 ng/ml, P<0.001). Islets from S5 hamsters released significantly more insulin than C5 islets in the presence of low and high glucose (3.3 mM glucose: 0.77 ± 0.04 vs 0.20 ± 0.06 pg/ng DNA/min, P<0.001; 16.7 mM glucose: 2.77 ± 0.12 vs 0.85 ± 0.06 pg/ng DNA/min, P<0.001) and produced significantly higher amounts of <SUP>14</SUP>CO<SUB>2</SUB> and <SUP>3</SUP>H<SUB>2</SUB>O at both glucose concentrations (<SUP>14</SUP>CO<SUB>2</SUB>: 3.3 mM glucose: 0.27 ± 0.01 vs 0.18 ± 0.01, P<0.001; 16.7 mM glucose: 1.44 ± 0.15 vs 0.96 ± 0.08, P<0.02; <SUP>3</SUP>H<SUB>2</SUB>O: 3.3 mM glucose: 0.31 ± 0.02 vs 0.15 ± 0.01, P<0.001; 16.7 mM glucose: 1.46 ± 0.20 vs 0.76 ± 0.05 pmol glucose/ng DNA/min, P<0.005). The hexokinase K<SUB>m</SUB> and V<SUB>max</SUB> values from S5 animals were significantly higher than those from C5 ones (K<SUB>m</SUB>: 100.14 ± 7.01 vs 59.90 ± 3.95 ♂M, P<0.001; V<SUB>max</SUB>: 0.010 ± 0.0005 vs 0.008 ± 0.0006 pmol glucose/ng DNA/min, P<0.02). Conversely, the glucokinase K<SUB>m</SUB> value from S5 animals was significantly lower than in C5 animals (K<SUB>m</SUB>: 15.31 ± 2.64 vs 35.01 ± 1.65 mM, P<0.001), whereas V<SUB>max</SUB> figures were within a comparable range in both groups (V<SUB>max</SUB>: 0.048 ± 0.009 vs 0.094 ± 0.035 pmol glucose/ng DNA/min, not significant). The glucose phosphorylation ratio measured at 1 and 100 mM (hexokinase/glucokinase ratio) was significantly higher in S5 (0.26 ± 0.02) than in C5 animals (0.11 ± 0.01, P<0.005), and it was attributable to an increase in the hexokinase activity in S5 animals. In conclusion, sucrose administration increased the hexokinase/glucokinase activity ratio in the islets, which would condition the increase in glucose metabolism by β-cells, and in β-cell sensitivity and responsiveness to glucose. These results support the concept that increased hexokinase rather than glucokinase activity causes the β-cell hypersensitivity to glucose, hexokinase being metabolically more active than glucokinase to up-regulate β-cell function. |
| format |
Articulo Articulo |
| author |
Massa, María Laura Borelli, María Inés Del Zotto, Héctor Herminio Gagliardino, Juan José |
| author_facet |
Massa, María Laura Borelli, María Inés Del Zotto, Héctor Herminio Gagliardino, Juan José |
| author_sort |
Massa, María Laura |
| title |
Changes induced by sucrose administration on glucose metabolism in pancreatic islets in normal hamsters |
| title_short |
Changes induced by sucrose administration on glucose metabolism in pancreatic islets in normal hamsters |
| title_full |
Changes induced by sucrose administration on glucose metabolism in pancreatic islets in normal hamsters |
| title_fullStr |
Changes induced by sucrose administration on glucose metabolism in pancreatic islets in normal hamsters |
| title_full_unstemmed |
Changes induced by sucrose administration on glucose metabolism in pancreatic islets in normal hamsters |
| title_sort |
changes induced by sucrose administration on glucose metabolism in pancreatic islets in normal hamsters |
| publishDate |
2001 |
| url |
http://sedici.unlp.edu.ar/handle/10915/84894 |
| work_keys_str_mv |
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