Integrated Pancreatic Blood Flow: Bidirectional Microcirculation Between Endocrine and Exocrine Pancreas
- 20 March 2020
- journal article
- research article
- Published by American Diabetes Association in Diabetes
- Vol. 69 (7), 1439-1450
- https://doi.org/10.2337/db19-1034
Abstract
The pancreatic islet is a highly vascularized endocrine micro-organ. The unique architecture of rodent islets, a so-called core-mantle arrangement seen in two-dimensional images, led researchers to seek functional implications for islet hormone secretion. Three models of islet blood flow were previously proposed, all based on the assumption that islet microcirculation occurs in an enclosed structure. Recent electrophysiological and molecular biological studies using isolated islets also presumed unidirectional flow. Using intravital analysis of the islet microcirculation in mice, we found that islet capillaries were continuously integrated to those in the exocrine pancreas, which made the islet circulation rather open, not self-contained. Similarly in human islets, the capillary structure was integrated with pancreatic microvasculature in its entirety. Thus, islet microcirculation has no relation to islet cytoarchitecture, which explains its well-known variability throughout species. Furthermore, tracking fluorescent-labeled red blood cells at the endocrine-exocrine interface revealed bidirectional blood flow, with similar variability in blood flow speed in both the intra- and extra-islet vasculature. To date, the endocrine and exocrine pancreas have been studied separately by different fields of investigators. We propose that the open circulation model physically links both endocrine and exocrine parts of the pancreas as a single organ through the integrated vascular network.Keywords
Funding Information
- National Institute of Diabetes and Digestive and Kidney Diseases (DK-117192, DK-020595)
This publication has 48 references indexed in Scilit:
- Vascular instruction of pancreas developmentDevelopment, 2012
- Neurogenin3 initiates stepwise delamination of differentiating endocrine cells during pancreas developmentDevelopmental Dynamics, 2011
- ‘Giving and taking’: endothelial and β-cells in the islets of LangerhansTrends in Endocrinology & Metabolism, 2010
- No mantle formation in rodent islets—The prototype of islet revisitedDiabetes Research and Clinical Practice, 2009
- Islet architecture: A comparative studyIslets, 2009
- Real-time, multidimensional in vivo imaging used to investigate blood flow in mouse pancreatic isletsJCI Insight, 2008
- Snail2, a mediator of epithelial-mesenchymal transitions, expressed in progenitor cells of the developing endocrine pancreasGene Expression Patterns, 2007
- Assessment of Human Pancreatic Islet Architecture and Composition by Laser Scanning Confocal MicroscopyJournal of Histochemistry & Cytochemistry, 2005
- Uvomorulin mediates calcium-dependent aggregation of islet cells, whereas calcium-independent cell adhesion molecules distinguish between islet cell typesDevelopmental Biology, 1991
- FUNCTIONAL SUBDIVISION OF ISLETS OF LANGERHANS AND POSSIBLE ROLE OF D CELLSThe Lancet, 1975