Vesicular quantal size measured by amperometry at chromaffin, mast, pheochromocytoma, and pancreatic β-cells

Jennifer M. Finnegan, Karin Pihel, Paula S. Cahill, Lan Huang, Susan E. Zerby, Andrew G. Ewing, Robert T. Kennedy, R. Mark Wightman

Research output: Contribution to journalArticlepeer-review

Abstract

Amperometric detection of exocytosis at single chromaffin cells has shown that the distribution of spike areas, or quantal size, is dependent on the volume and catecholamine concentration of individual secretory vesicles. The present work offers an alternate, simplified model to analyze the current spikes due to single exocytotic events. When the cube root of these spike areas is plotted as a histogram, a Gaussian distribution is obtained for chromaffin cells and also mast, pheochromocytoma, and pancreatic β-cells. It was found that the relative SD of these distributions is similar to that for the vesicular radii, which also have a Gaussian distribution in all four cell types. In addition, this model was used to evaluate conditions where the quantal size of individual events was altered. When chromaffin cells were maintained in culture for <6 days, spikes of approximately double the quantal size were obtained on repeated exposure to 60 mM K+. The results suggest a heterogeneous distribution of catecholamine-containing vesicles at later days in culture is responsible for this alteration.

Original languageEnglish (US)
Pages (from-to)1914-1923
Number of pages10
JournalJournal of neurochemistry
Volume66
Issue number5
DOIs
StatePublished - May 1996

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cellular and Molecular Neuroscience

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