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.
Bibliographical noteFunding Information:
We acknowledge funding from the European Research Council (Advanced Grant), the Knut and Alice Wallenberg Foundation, the Swedish Research Council (VR). AH acknowledges funding from Sweden's Innovation Agency (Vinnova) and the Swedish Strategy Group for EU‐coordination. Also, AH thanks Alicia Lork for critical comments on the manuscript. NRG was supported by the European Foundation for the Study of Diabetes‐Rising Star Program and Novo Nordisk Foundation‐Young Investigator Program.
© 2020 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH
- beta cells
- electrochemical analysis
- partial release