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 alpha 1-macroglobulin, the major circulating protease inhibitor of rats, and the complex was cleared in a biexponential manner: t1/2 of the fast component . 1.8 +2- 0.1 min; t1/2 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 alpha 1-macroglobulin (the rat equivalent of human alpha 2-macroglobulin), which once formed is quickly eliminated from the bloodstream by tissue uptake and metabolized.
- Research Organization:
- Department of Physiology, The University of Sydney, New South Wales, Australia
- OSTI ID:
- 6493079
- 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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551001 -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMISTRY
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BODY FLUIDS
CHEMISTRY
CLEARANCE
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
EXCRETION
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MATERIALS
METABOLISM
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
RATS
RENAL CLEARANCE
RODENTS
TRACER TECHNIQUES
URINE
VERTEBRATES
WASTES