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Horm Metab Res 1972; 4(2): 83-86
DOI: 10.1055/s-0028-1094105
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© Georg Thieme Verlag KG Stuttgart · New York

Enzymatic Studies of Glucose Phosphorylation in the Glucagon-Producing Cells of Duck Pancreas[*]

G.  Lundqvist
  • Histological Department, University of Uppsala, Uppsala, Sweden
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Publication History

Publication Date:
07 January 2009 (online)

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Abstract

The glucagon-producing A2-cells of the pancreatic islets seem to show a reversed secretory response to glucose in comparison with the insulin-producing B-cells. In this investigation, the glucose phosphorylating process has been studied in A2-cells isolated from cryostat sections of duck pancreases. The cell samples were prepared by free-hand dissection in cold heptane during observation with a dark field stereo microscope.

Measurements of the hexokinase activity at high and low glucose concentrations indicated a low phosphorylating capacity of the A2-cells. Hexokinase activity was about 0.15 MKH (moles substrate converted per kg dry weight per hour of incubation). Km was between 3 × 10-5 and 4 × 10-5M. Comparisons of nexokinase activity were made with pancreatic acini, liver and heart muscle. No high-Km hexokinase was found in the A2-cells, while the presence of glucokinase was easily demonstrated in the liver.

These results strongly suggest that the phosphorylation of glucose in the A2-cells is of lower regulatory importance than in the B-cells.

Key words

Isolated A2-cells - Phosphorylation of Glucose - Hexokinase - Glucagon

1 Supported by the Swedish Medical Research Council (Project No. B71-12X-525-07C), the Medical Faculty of Uppsala, The Swedish Diabetes Association and the Åhlén Foundation.

1 Supported by the Swedish Medical Research Council (Project No. B71-12X-525-07C), the Medical Faculty of Uppsala, The Swedish Diabetes Association and the Åhlén Foundation.