Clearance and metabolism of /sup 125/I-labeled tonin in the rat
/sup 125/I-labeled rat tonin was injected iv into male Wistar rats weighing 303 +/- 17 g (mean +/- SE), and the disappearance from the circulation, plasma interaction, tissue uptake, and metabolism of radioactivity was studied. After injection, /sup 125/I-labeled tonin was immediately bound by ..cap alpha../sub 1/-macroglobulin, the major circulating protease inhibitor of rats, and the complex was cleared in a biexponential manner: t/sub 1///sub 2/ of the fast component = 1.8 +/- 0.1 min; t/sub 1///sub 2/ of the slow component = 84 +/- 10 min; MCR = 2.1 +/- 0.2 ml/min (mean +/- SE, N = 8). The complex was taken up intact by tissues, the major ones being the liver, spleen, adrenal, thyroid, and kidney. Analysis of tissue extracts by gel filtration on Sephadex G-100 showed that the kidney was the major site of metabolism, and radioactivity similar in size to /sup 125/I appeared rapidly in urine. Therefore tonin circulates wholly as a complex with ..cap alpha../sub 1/-macroglobulin (the rat equivalent of human ..cap alpha../sub 2/-macroglobulin), which once formed is quickly eliminated from the bloodstream by tissue uptake and metabolized.
- Research Organization:
- Univ. of Sydney, Australia
- OSTI ID:
- 6173119
- Journal Information:
- Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 111:5; ISSN ENDOA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ADRENAL GLANDS
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BLOOD-PLASMA CLEARANCE
BODY
CLEARANCE
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
ENZYME INHIBITORS
ENZYMES
GLANDS
GLOBULINS
GLOBULINS-ALPHA
HYDROLASES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
KINETICS
LABELLED COMPOUNDS
LIVER
MAMMALS
METABOLISM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HYDROLASES
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RODENTS
SPLEEN
THYROID
TRACER TECHNIQUES
UPTAKE
VERTEBRATES