Effects of intravesicular H+ and extracellular H+ and Zn2+ on insulin secretion in pancreatic beta cells

Craig A Aspinwall, Sunday A. Brooks, Robert T. Kennedy, Jonathan R T Lakey

Research output: Contribution to journalArticle

76 Citations (Scopus)

Abstract

The effects of extracellular Zn2+ and pH and intravesicular pH on insulin and 5-hydroxytryptamine (5-HT) secretion from pancreatic beta cells were investigated. Insulin and 5-HT secretion from single cells was detected by amperometry as a series of current spikes corresponding to detection of multimolecular packets secreted by exocytosis. Spike width was used as a measure of the kinetics of clearance from the cell and the area of spikes as a measure of amount released. Changes in extracellular pH from 6.9 to 7.9 caused insulin spikes to become narrower with no change in area, whereas the same treatments had no effect on 5-HT secretion. Treatment of cells with Bafilomycin A1 or N-ethylmaleimide, both of which are expected to increase intravesicular pH by inhibiting V-type H+-ATPase, had no effect on 5-HT secretion but caused insulin spikes to become more narrow. These results indicate that exposure to high pH, whether intravesicular or extracellular, accelerates release of insulin during exocytosis without affecting the amount of insulin released. Increasing extracellular Zn2+ concentration from 0 to 25 μM increased the width and decreased the area of insulin spikes without affecting 5-HT secretion. Zn2+ effects were likely exerted through a common-ion effect on Zn2+-insulin dissociation. It was concluded that intravesicular storage conditions and extracellular ions can affect free insulin concentration in the vicinity of beta cells during secretion.

Original languageEnglish (US)
Pages (from-to)31308-31314
Number of pages7
JournalJournal of Biological Chemistry
Volume272
Issue number50
DOIs
StatePublished - Dec 12 1997
Externally publishedYes

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Insulin-Secreting Cells
Insulin
Serotonin
Exocytosis
Ions
Vacuolar Proton-Translocating ATPases
Ethylmaleimide
Proton-Translocating ATPases
Cells
Kinetics

ASJC Scopus subject areas

  • Biochemistry

Cite this

Effects of intravesicular H+ and extracellular H+ and Zn2+ on insulin secretion in pancreatic beta cells. / Aspinwall, Craig A; Brooks, Sunday A.; Kennedy, Robert T.; Lakey, Jonathan R T.

In: Journal of Biological Chemistry, Vol. 272, No. 50, 12.12.1997, p. 31308-31314.

Research output: Contribution to journalArticle

Aspinwall, Craig A ; Brooks, Sunday A. ; Kennedy, Robert T. ; Lakey, Jonathan R T. / Effects of intravesicular H+ and extracellular H+ and Zn2+ on insulin secretion in pancreatic beta cells. In: Journal of Biological Chemistry. 1997 ; Vol. 272, No. 50. pp. 31308-31314.
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