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Transcytosis of insulin across microvascular endothelium
Author(s) -
Azizi Paymon Michael,
Wang Changsen,
Armstrong Susan M,
Klip Amira,
Lee Warren L
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1154.11
Subject(s) - transcytosis , paracellular transport , transcellular , insulin , endothelium , microbiology and biotechnology , medicine , endocrinology , biology , chemistry , endocytosis , biochemistry , permeability (electromagnetism) , receptor , membrane
Circulating plasma insulin concentrations are higher than those of the interstitium, suggesting that transport across the microvascular endothelial layer is the rate‐limiting step. It is hypothesized that the metabolic syndrome, characterized by insulin resistance, is influenced by alterations in the trans‐endothelial transport of insulin. However, little is known about how insulin crosses the microvascular endothelium, although in principle it could occur via a paracellular or transcellular route. To date, technical limitations have limited the study of insulin transcytosis. Here we show the development of transwell and total internal reflectance fluorescence microscopy (TIRFM) assays to quantify transcytosis of insulin across endothelial monolayers. The transwell assay measures only the transcellular permeability of insulin and TIRFM measures the fusion of insulin‐containing vesicles at the basal membrane; neither assay is affected by paracellular leak. Using these complementary methods, we show that insulin transcytosis across tissue microvessels is a receptor‐mediated process. Further, that microtubule depolymerization decreases insulin transcytosis. In conclusion, we have developed methods for quantifying the transcytosis of insulin across the microvascular endothelium. We will thus discuss insulin transcytosis under conditions mimicking the metabolic syndrome.