Luminal and basolateral uptake of insulin in isolated perfused, proximal tubules

Journal Article · Sun Nov 01 04:00:00 EST 1987 · American Journal of Physiology; (USA)

OSTI ID:6834217

Nielsen, S; Nielsen, J T; Christensen, E I ^[1]

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1. Univ. of Aarhus (Denmark)

The present study was performed to quantitate compare the luminal and the peritubular uptake of {sup 125}I-insulin in isolated, perfused, proximal tubules from rabbit kidneys. {sup 125}I-insulin was added in physiological concentrations to either the perfusate or the bath fluid for 30 min. The luminal uptake in 30 min averaged 0.76 pg/mm at physiological concentrations and 18.0 pg/mm at high insulin concentrations. About 15-41% of the absorbed insulin was digested and <5% was transported from the lumen to the peritubular space as intact insulin. The peritubular binding/uptake of {sup 125}I-insulin at physiological and high concentrations in the bath was 0.136 and 0.318 pg, respectively. The data indicates that insulin is bound/absorbed at the basolateral membranes both by a saturable specific mechanism and a nonspecific, nonsaturable mechanism. The basolateral absorption constituted 15.2 and 1.8% of the total tubular extraction of insulin at physiological and high insulin concentrations, respectively. Electron microscope autoradiography showed that, after luminal as well as basolateral endocytosis, insulin was exclusively accumulated in endocytic vacuoles and lysosomes.

• OSTI ID: 6834217
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 253:5; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BODY
CARBOHYDRATES
CARBON 14 COMPOUNDS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELECTRON MICROSCOPY
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
INULIN
IODINE 125
IODINE ISOTOPES
ISOTOPES
KIDNEYS
LABELLED COMPOUNDS
MAMMALS
MICROSCOPY
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
POLYSACCHARIDES
RABBITS
RADIOISOTOPES
SACCHARIDES
TRANSMISSION ELECTRON MICROSCOPY
TUBULES
UPTAKE
VERTEBRATES