Luminal uptake and intracellular transport of insulin in renal proximal tubules

Journal Article · Thu May 01 04:00:00 EDT 1986 · Kidney Int.; (United States)

DOI:https://doi.org/10.1038/ki.1986.97· OSTI ID:5004782

Hellfritzsch, M; Christensen, E I; Sonne, O

It is generally accepted that proteins taken up from the renal tubular fluid are transported into lysosomes in proximal tubule cells. Recently, however, it has been postulated that insulin in isolated perfused rat kidneys did not accumulate in lysosomes but to a certain degree in the Golgi region. The present study was undertaken to investigate the intracellular handling of biologically unaltered insulin in rat renal proximal tubule cells. Rats were prepared for in vivo micropuncture and either a colloidal gold insulin complex or insulin monoiodinated in the A-14 position (/sup 125/I-insulin) was microinfused into proximal tubules. After 5, 10, 25 or 60 min the tubules were fixed by microinfusion of glutaraldehyde and processed for electron microscopy or electron microscope autoradiography. A qualitative analysis of tubules infused with colloidal gold insulin or /sup 125/I-insulin showed that insulin was taken up by endocytosis and transported to lysosomes, and a quantitative autoradiographic analysis of the /sup 125/I-insulin microinfused tubules showed that the grain density after five min was significantly increased for endocytic vacuoles and for lysosomes. After 60 min the grain density was still significant over lysosomes. The accumulation of grains was non-significant over all other areas analyzed at any time. This study shows that insulin is taken up from the luminal side of the proximal tubule by endocytosis and transported to the lysosomes. There was no significant transport to the Golgi region.

• OSTI ID: 5004782
• Journal Information: Kidney Int.; (United States), Journal Name: Kidney Int.; (United States) Vol. 5; ISSN KDYIA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
COLLOIDS
DAYS LIVING RADIOISOTOPES
DISPERSIONS
ELECTRON CAPTURE RADIOISOTOPES
ELECTRON MICROSCOPY
ELEMENTS
GOLD
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
LABELLED COMPOUNDS
LYSOSOMES
MAMMALS
METALS
MICROSCOPY
NUCLEI
ODD-EVEN NUCLEI
ORGANOIDS
ORGANS
PEPTIDE HORMONES
RADIOISOTOPES
RATS
RODENTS
TRACER TECHNIQUES
TRANSITION ELEMENTS
TUBULES
UPTAKE
VERTEBRATES