Nanoscale Amperometry Reveals that Only a Fraction of Vesicular Serotonin Content is Released During Exocytosis from Beta Cells

• Recent work has shown that chemical release during the fundamental cellular process of exocytosis in model cell lines is not all-or-none. We tested this theory for vesicular release from single pancreatic beta cells. The vesicles in these cells release insulin, but also serotonin, which is detectible with amperometric methods. Traditionally, it is assumed that exocytosis in beta cells is all-or-none. Here, we use a multidisciplinary approach involving nanoscale amperometric chemical methods to explore the chemical nature of insulin exocytosis. We amperometrically quantified the number of serotonin molecules stored inside of individual nanoscale vesicles (39 317 +/- 1611) in the cell cytoplasm before exocytosis and the number of serotonin molecules released from single cells (13 310 +/- 1127) for each stimulated exocytosis event. Thus, beta cells release only one-third of their granule content, clearly supporting partial release in this system. We discuss these observations in the context of type-2 diabetes.

Subject headings

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

Keyword

beta cells

electrochemical analysis

exocytosis

nanoelectrodes

partial release

Chemistry

Publication and Content Type

ref (subject category)

art (subject category)