Tissue locations for the turnover of radioactively labeled rat orosomucoid in vivo
Tissues involved in the turnover of rat serum orosomucoid were identified by methods designed to cause lysosomal trapping of radiolabel at the sites of glycoprotein degradation. /sup 125/I-, (/sup 3/H)Raffinose-, and (1-/sup 14/C)glucosamine-labeled orosomucoid exhibited serum half-lives of 20, 20, and 27 h when injected intravenously into rats. As expected, the asialo derivative of (/sup 3/H)raffinose-labeled rat orosomucoid was lost very rapidly from the circulation and recovered quantitatively in the liver within 30 min. At 50 h after injection of (/sup 3/H)raffinose-asialo-orosomucoid the liver retained 38% of the radioactivity while the remainder was found in the gastrointestinal tract and urine. Chromatography of the urine on Bio-Gel P-4 revealed a single radioactive product that eluted similar to raffinose-lysine. The same material was found in the liver. This ability of the (/sup 3/H)raffinose label to resist metabolic disposal was used to evaluate tissue catabolism of native rat orosomucoid. Comparison of the tissue radioactivity in experiments using /sup 125/I- and (/sup 3/H)raffinose-labeled derivatives of the nondesialylated glycoprotein showed kidney, liver, and muscle to be most active in /sup 3/H accumulation. However, the (/sup 3/H)raffinose metabolites excreted in the urine was markedly different from those produced from asialo-orosomucoid and in contrast there was minimal loss of label to the gastrointestinal tract from the native substrate. At 24 h after injection of /sup 125/I-orosomucoid, leupeptin-treated rats showed a net 16% increase in tissue radioactivity above sham-operated animals and a corresponding decrease occurred in the radioactivity associated with the gastrointestinal tract and urine. Tissues that exhibited increases in radioactivity were kidney, muscle, liver, and hide.
- Research Organization:
- Biochemistry Program, Althouse Laboratory, Pennsylvania State University, University Park
- OSTI ID:
- 5504949
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Vol. 224:2
- Country of Publication:
- United States
- Language:
- English
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MUCOPROTEINS
METABOLISM
TISSUE DISTRIBUTION
CARBON 14
GASTROINTESTINAL TRACT
GLUCOPROTEINS
IODINE 125
KIDNEYS
LABELLING
LIVER
RAFFINOSE
RATS
TRITIUM
URINE
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BODY
BODY FLUIDS
CARBOHYDRATES
CARBON ISOTOPES
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DISTRIBUTION
ELECTRON CAPTURE RADIOISOTOPES
EVEN-EVEN NUCLEI
GLANDS
HYDROGEN ISOTOPES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
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LIGHT NUCLEI
MAMMALS
MATERIALS
NUCLEI
ODD-EVEN NUCLEI
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
ORGANS
POLYSACCHARIDES
PROTEINS
RADIOISOTOPES
RODENTS
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550501* - Metabolism- Tracer Techniques