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Paradoxical stimula...
Paradoxical stimulation of glucagon secretion by high glucose concentrations
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- Salehi, S Albert (author)
- Lund University,Lunds universitet,Islet cell physiology,Forskargrupper vid Lunds universitet,Lund University Research Groups,Institutionen för klinisk vetenskap, Malmö universitetssjukhus, Lunds universitet
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- Vieira, Elaine (author)
- Uppsala universitet,Institutionen för medicinsk cellbiologi
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- Gylfe, Erik (author)
- Uppsala universitet,Institutionen för medicinsk cellbiologi
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(creator_code:org_t)
- American Diabetes Association, 2006
- 2006
- English.
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In: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 55:8, s. 2318-2323
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Abstract
Subject headings
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- Hypersecretion of glucagon contributes to the dysregulation of glucose homeostasis in diabetes. To clarify the underlying mechanism, glucose-regulated glucagon secretion was studied in mouse pancreatic islets and clonal hamster In-R1-G9 glucagon-releasing cells. Apart from the well-known inhibition of secretion with maximal effect around 7 mmol/l glucose, we discovered that mouse islets showed paradoxical stimulation of glucagon release at 25-30 mmol/l and In-R1-G9 cells at 12-20 mmol/l sugar. Whereas glucagon secretion in the absence of glucose was inhibited by hyperpolarization with diazoxide, this agent tended to further enhance secretion stimulated by high concentrations of the sugar. Because U-shaped dose-response relationships for glucose-regulated glucagon secretion were observed in normal islets and in clonal glucagon-releasing cells, both the inhibitory and stimulatory components probably reflect direct effects on the a-cells. Studies of isolated mouse a-cells indicated that glucose inhibited glucagon secretion by lowering the cytoplasmic Ca2+ concentration. However, stimulation of glucagon release by high glucose concentrations did not require elevation of Ca2+, indicating involvement of novel mechanisms in glucose regulation of glucagon secretion. A U-shaped dose-response relationship for glucose-regulated glucagon secretion may explain why diabetic patients with pronounced hyperglycemia display paradoxical hyperglucagonemia.
Subject headings
- MEDICIN OCH HÄLSOVETENSKAP -- Medicinska och farmaceutiska grundvetenskaper -- Cell- och molekylärbiologi (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Basic Medicine -- Cell and Molecular Biology (hsv//eng)
- MEDICIN OCH HÄLSOVETENSKAP -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)
- MEDICIN OCH HÄLSOVETENSKAP -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Basic Medicine -- Physiology (hsv//eng)
Keyword
- [Ca2+]i
- cytoplasmic Ca2+ concentration
- KATP channel
- ATP-sensitive K+ channel
- Cell biology
- Cellbiologi
- Diabetology
- Diabetologi
- Physiology
- Fysiologi
- Medical Cell Biology
- Medicinsk cellbiologi
Publication and Content Type
- ref (subject category)
- art (subject category)
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