Evidence for multiple pathways of sup 125 I-insulin internalization in isolated rat hepatocytes

Thesis/Dissertation · Fri Jan 01 00:00:00 EST 1988

OSTI ID:7147008

Moss, A L

Insulin internalization has been characterized frequently as occurring by the coated pit pathway of receptor-mediated endocytosis. The present study in rat hepatocytes demonstrates that insulin internalization is, in part, receptor-mediated, but also occurs by nonreceptor-mediated or fluid-phase endocytosis. Endocytosis was probed with four perturbations: depletion of metabolic energy with anoxia, inhibition of endocytosis with phenylarsine oxide, disruption of coated pits with hyperosmolar sucrose, and inhibition of receptor recycling or ligand-receptor dissociation with monensin. Internalization of {sup 125}I-epidermal growth factor and {sup 125}I-asialofetuin was compared to {sup 125}I-insulin internalization. Pretreatment of cells with anoxia or hyperosmolarity inhibited {sup 125}I-insulin internalization by 40%; pretreatment with phenylarsine oxide resulted in inhibition by 54%. Monensin has no effect on uptake or degradation of a high insulin concentration, but inhibited degradation of a low insulin concentration resulting in intracellular accumulation of insulin. In contract, all four perturbations inhibited {sup 125}I-asialofetuin internalization by greater than 90%. Phenylarsine oxide almost completely abolished {sup 125}I-epidermal growth factor uptake; the other perturbations caused partial inhibition. Competition studies demonstrated that insulin internalization was receptor-mediated over a wide concentration range.

• Research Organization: Texas Univ., San Antonio, TX (USA). Health Science Center
• OSTI ID: 7147008
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
INSULIN
METABOLISM
ANOXIA
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
GROWTH FACTORS
INHIBITION
IODINE 125
LIGANDS
LIVER CELLS
RATS
RECEPTORS
TRACER TECHNIQUES
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MITOGENS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
SOMATIC CELLS
VERTEBRATES
550501* - Metabolism- Tracer Techniques