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- Gromada, J, et al.
(author)
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Adrenaline stimulates glucagon secretion in pancreatic A-cells by increasing the Ca2+ current and the number of granules close to the L-type Ca2+ channels.
- 1997
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In: The Journal of General Physiology. - 0022-1295 .- 1540-7748. ; 110:3, s. 217-28
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Journal article (peer-reviewed)abstract
- We have monitored electrical activity, voltage-gated Ca2+ currents, and exocytosis in single rat glucagon-secreting pancreatic A-cells. The A-cells were electrically excitable and generated spontaneous Na+- and Ca2+-dependent action potentials. Under basal conditions, exocytosis was tightly linked to Ca2+ influx through omega-conotoxin-GVIA-sensitive (N-type) Ca2+ channels. Stimulation of the A-cells with adrenaline (via beta-adrenergic receptors) or forskolin produced a greater than fourfold PKA-dependent potentiation of depolarization-evoked exocytosis. This enhancement of exocytosis was due to a 50% enhancement of Ca2+ influx through L-type Ca2+ channels, an effect that accounted for <30% of the total stimulatory action. The remaining 70% of the stimulation was attributable to an acceleration of granule mobilization resulting in a fivefold increase in the number of readily releasable granules near the L-type Ca2+ channels.
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