Intracellular pathways of insulin transport across vascular endothelial cells
Processing and transport of hormones across vascular endothelial cells may modulate hormone action at subendothelial tissue sites. Insulin was transported across cultured rat capillary and bovine aortic endothelial cells, after a delay of 5-10 min, at a constant rate for 60 min at 37 degrees C. 125I-labeled insulin transport was inhibited by 88 +/- 11% (SE, n = 4) and 75 +/- 18% (SE, n = 4) in the presence of anti-insulin receptor antibody and unlabeled insulin (at 10(-7) M), respectively. Reverse phase high-performance liquid chromatography showed 88% of the 125I-insulin transported over 60 min was indistinguishable from the 125I-insulin added to the cells at 4 degrees C. In aortic endothelial cells preincubated with 2.3 x 10(-9) M of insulin for 24 h, insulin receptor binding was downregulated by 67%, and 125I-insulin transport was decreased by 52 +/- 11%. The proton ionophore monensin (0.05 mM) increased the internalized insulin in bovine aortic endothelial cells by 78%, with a corresponding decrease in 125I-insulin released by 76 +/- 2% (SE, n = 4). 125I-insulin transport across the aortic endothelial cell monolayer was similarly decreased (54 +/- 12%, SE, n = 4) by monensin. In contrast, the lysosomal protease inhibitor leupeptin had no effect. Degradation and transport were similarly dissociated by low temperature. At 15 degrees C, no significant insulin degradation was detected, whereas 125I-insulin release from the cells continued at 30 +/- 3% of the rate at 37 degrees C.
- Research Organization:
- Harvard Medical School, Boston, MA (USA)
- OSTI ID:
- 6583629
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 255; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ANIMAL TISSUES
ANIMALS
AORTA
ARTERIES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
BLOOD VESSELS
BODY
CAPILLARIES
CARDIOVASCULAR SYSTEM
CATTLE
CELL CULTURES
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ELECTRON CAPTURE RADIOISOTOPES
ENDOTHELIUM
ENZYME INHIBITORS
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIQUID COLUMN CHROMATOGRAPHY
MAMMALS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
RUMINANTS
SEPARATION PROCESSES
TISSUES
TRACER TECHNIQUES
VERTEBRATES