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Tight coupling betw...
Tight coupling between electrical activity and exocytosis in mouse glucagon-secreting alpha-cells
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- Barg, Sebastian (författare)
- Lund University,Lunds universitet,Islet cell physiology,Forskargrupper vid Lunds universitet,Lund University Research Groups
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Galvanovskis, J (författare)
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Gopel, S O (författare)
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- Rorsman, Patrik (författare)
- Lund University,Lunds universitet,Islet cell physiology,Forskargrupper vid Lunds universitet,Lund University Research Groups
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- Eliasson, Lena (författare)
- Lund University,Lunds universitet,Diabetes - öcellsexocytos,Forskargrupper vid Lunds universitet,Diabetes - Islet Cell Exocytosis,Lund University Research Groups
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(creator_code:org_t)
- 2000
- 2000
- Engelska.
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Ingår i: Diabetes. - 1939-327X .- 0012-1797. ; 49:9, s. 1500-1510
- Relaterad länk:
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http://diabetes.diab... (free)
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https://lup.lub.lu.s...
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- alpha-Cells were identified in preparations of dispersed mouse islets by immunofluorescence microscopy. A high fraction of alpha-cells correlated with a small cell size measured as the average cell diameter (10 microm) and whole-cell capacitance (<4 pF). The alpha-cells generated action potentials at a low frequency (1 Hz) in the absence of glucose. These action potentials were reversibly inhibited by elevation of the glucose concentration to 20 mmol/l. The action potentials originated from a membrane potential more negative than -50 mV, had a maximal upstroke velocity of 5 V/s, and peaked at +1 mV. Voltage-clamp experiments revealed the ionic conductances underlying the generation of action potentials. alpha-Cells are equipped with a delayed tetraethyl-ammonium-blockable outward current (activating at voltages above -20 mV), a large tetrodotoxin-sensitive Na+ current (above -30 mV; peak current 200 pA at +10 mV), and a small Ca2+ current (above -50 mV; peak current 30 pA at +10 mV). The latter flowed through omega-conotoxin GVIA (25%)- and nifedipine-sensitive (50%) Ca(2+)-channels. Mouse alpha-cells contained, on average, 7,300 granules, which undergo Ca(2+)-induced exocytosis when the alpha-cell is depolarized. Three functional subsets of granules were identified, and the size of the immediately releasable pool was estimated as 80 granules, or 1% of the total granule number. The maximal rate of exocytosis (1.5 pF/s) was observed 21 ms after the onset of the voltage-clamp depolarization, which is precisely the duration of Ca(2+)-influx during an action potential. Our results suggest that the secretory machinery of the alpha-cell is optimized for maximal efficiency in the use of Ca2+ for exocytosis.
Ämnesord
- MEDICIN OCH HÄLSOVETENSKAP -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)
Publikations- och innehållstyp
- art (ämneskategori)
- ref (ämneskategori)
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