Imaging of Zn2+ release from pancreatic beta-cells at the level of single exocytotic events

Anal Chem. 2003 Jul 15;75(14):3468-75. doi: 10.1021/ac0341057.


Regulated secretion of Zn2+ from isolated pancreatic beta-cells was imaged using laser-scanning confocal microscopy. In the method, beta-cells were incubated in a solution containing the novel fluorescent Zn2+ indicator FluoZin-3. Zn2+ released from the cells reacted with the dye to form a fluorescent product, which was detected by the confocal microscope. The new dye is much brighter than Zinquin, previously used for this application, allowing detection limits of 10-40 nM and temporal resolution of 16 ms/image. The high temporal resolution allowed imaging of isolated fluorescent transients that occurred at the edge of the cells following stimulation with 20 mM glucose or 40 mM K+. Fluorescent transients took 16-50 ms to reach a peak from the initial rise and returned to baseline after 170 +/- 50 ms (n = 78 transients from 15 cells). It was concluded that the transients correspond to detection of exocytotic release of Zn2+. Analysis of the temporal and spatial dispersion of the transients indicates that the release of Zn2+ is not diffusion limited but is instead kinetically controlled in agreement with previous observations of insulin release detected by amperometry.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Exocytosis*
  • Indicators and Reagents
  • Islets of Langerhans / metabolism*
  • Islets of Langerhans / ultrastructure
  • Mice
  • Microscopy, Confocal
  • Polycyclic Compounds
  • Zinc / chemistry
  • Zinc / metabolism*


  • FluoZin-3
  • Indicators and Reagents
  • Polycyclic Compounds
  • Zinc