In vivo behavior of radioiodinated rabbit antithrombin III. Demonstration of a noncirculating vascular compartment
Rabbit antithrombin III (AT), was labeled with iodine-131 by either the glucose oxidase-lactoperoxidase or iodine monochloride techniques. When intravenously injected, the disappearance of the /sup 131/I-AT from plasma was characterized by rapid initial decreases, and three-exponential equations were required for best fit of the plasma disappearance curves. This rapid /sup 131/I-AT removal was not caused by denaturation, as shown by comparison with results obtained when /sup 131/I-AT was biologically screened (injected into a first rabbit, and then transferred 16 h later in whole plasma to a second for kinetic evaluation) before injection. Thus, the same rapid initial loss of plasma /sup 131/I-AT was observed with screened preparations, and the plasma fractional catabolic rates of 0.716 +/- 0.048 and 0.673 +/- 0.051 day-1 for unscreened and screened /sup 131/I-AT were not significantly different. These results support the hypothesis that a vascular-endothelial AT compartment is present in rabbit. The fractions of the total-body AT in the plasma, the vascular-endothelial and the extravascular compartments were 0.337 +/- 0.031, 0.178 +/- 0.056, and 0.485 +/- 0.069, respectively. Two three-compartment kinetic models are discussed. The first pictures AT as distributing independently between plasma and two other compartments, and the second sees AT as first passing to the vascular-endothelial compartment, and then directly into the extravascular compartment. The plasma /sup 131/I-AT kinetic data was consistent with both models, but the sizes of the vascular-endothelial compartments were best predicted by the second. If AT catabolism was assigned to the plasma, both models generally underpredicted the whole-body radioactivities, while assignment of breakdown to the extravascular compartment generally resulted in overpredictions. This suggests that AT catabolism occurs from both plasma and extravascular compartments.
- Research Organization:
- Univ. of New Mexico School of Medicine, Albuquerque
- OSTI ID:
- 6306149
- Journal Information:
- J. Clin. Invest.; (United States), Journal Name: J. Clin. Invest.; (United States) Vol. 74:1; ISSN JCINA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
ANTICOAGULANTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BIOLOGICAL MODELS
BLOOD
BLOOD PLASMA
BODY FLUIDS
DAYS LIVING RADIOISOTOPES
DRUGS
HALOGEN COMPOUNDS
HEMATOLOGIC AGENTS
INJECTION
INTAKE
INTERMEDIATE MASS NUCLEI
INTRAVENOUS INJECTION
IODINE 131
IODINE COMPOUNDS
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MATERIALS
NUCLEI
ODD-EVEN NUCLEI
PHYSIOLOGY
RABBITS
RADIOISOTOPES
REACTION KINETICS
TRACER TECHNIQUES
VERTEBRATES