Plasma clearance of human extracellular-superoxide dismutase C in rabbits

Journal Article · Thu Sep 01 04:00:00 EDT 1988 · J. Clin. Invest.; (United States)

DOI:https://doi.org/10.1172/JCI113676· OSTI ID:6703011

Karlsson, K; Marklund, S L

Extracellular-superoxide dismutase (EC-SOD) is heterogenous in the vasculature with regard to heparin affinity and can be separated into three fractions: A, without affinity; B, with weak affinity; and C, with relatively strong heparin affinity. The plasma clearance of intravenously injected 125I-labeled and unlabeled human EC-SOD C was studied in rabbits. About 90% of injected 125I-EC-SOD C was eliminated from the blood within 5-10 min. Injection of heparin after 10 or 20 min led to an immediate release of all sequestered 125I-EC-SOD C back to the blood plasma. Later injections of heparin led to diminished release, although release could still be demonstrated after 72 h. A half-time of approximately 10 h could be calculated for heparin-releasable 125I-EC-SOD C. Unlabeled EC-SOD C, determined as enzymic activity and with ELISA, was likewise sequestered and released to the same degree as 125I-labeled EC-SOD C by heparin as tested at 20 min and 5 h. The immediacy of the heparin-induced release indicates that the sequestered enzyme had been bound to endothelial cell surfaces. The length of the half-time suggests that the putative cell surface binding has a physiological function and is not primarily a step in enzyme degradation. The distribution of sequestered 125I-labeled EC-SOD C to different organs was determined at times between 10 min and 24 h. Of the organs, the liver contained the most 125I-EC-SOD C, followed by kidney, spleen, heart, and lung. At all investigated times, the content in the analyzed organs was nearly as large as the amount that could be promptly released to plasma by intravenous heparin. This indicates that almost all 125I-EC-SOD C in the organs was present on endothelial cell surfaces and was not bound by other tissue cell surfaces, or was present within the cells.

• Research Organization: Umea University Hospital (Sweden)
• OSTI ID: 6703011
• Journal Information: J. Clin. Invest.; (United States), Journal Name: J. Clin. Invest.; (United States) Vol. 82:3; ISSN JCINA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFFINITY
AMINES
ANIMAL TISSUES
ANIMALS
ANTICOAGULANTS
BETA DECAY RADIOISOTOPES
BIOLOGICAL HALF-LIFE
BLOOD-PLASMA CLEARANCE
BODY
CARBOHYDRATES
CLEARANCE
DAYS LIVING RADIOISOTOPES
DISTRIBUTION
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ENDOTHELIUM
ENZYME ACTIVITY
ENZYME IMMUNOASSAY
ENZYMES
EXTRACELLULAR SPACE
HEMATOLOGIC AGENTS
HEPARIN
IMMUNOASSAY
INJECTION
INTAKE
INTERMEDIATE MASS NUCLEI
INTRAVENOUS INJECTION
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
METABOLISM
MUCOPOLYSACCHARIDES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDOREDUCTASES
POLYSACCHARIDES
RABBITS
RADIOISOTOPES
SACCHARIDES
SPACE
SUPEROXIDE DISMUTASE
TISSUE DISTRIBUTION
TISSUES
TRACER TECHNIQUES
VERTEBRATES