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Abstract
The rates of synthesis and degradation of hemopexin (Hx) were studied in vivo to determine
the cause of altered serum levels of this protein as seen in hemolytic anemias, chronic
neuromuscular diseases, and acute intermittent porphyria. The synthetic and fractional
catabolic rates of Hx were measured in patients exhibiting low, normal, or elevated
serum Hx levels. It was found that the elevated levels were mainly due to increased
synthesis rather than decreased catabolism of Hx. In patients with elevated serum
Hx levels, the mean synthetic rate of Hx (13 ± 1.0 mg/kg/day) was twice that of the
patients with normal Hx levels (6.6 ± 0.3), whereas the fractional catabolic rate
was 35.3 ± 7.1% of the i.v. pool per day vs. 26.5 ± 0.8 for controls. The low serum
Hx levels observed in patients with sickle cell anemia appeared to be due to increased
Hx catabolism (36.0 and 40.0% of the i.v. pool per day vs. 26.5 ± 0.8 for controls)
with no compensatory increase in synthesis. This latter finding is in agreement with
a study in rhesus monkeys in which repeated administration of a large dose of heme
caused an increase in the catabolism of hemopexin without a concurrent increase in
its synthesis (J Lab Clin Med 100:451, 1982). Our results indicate that although both synthesis and catabolism are increased
in patients with elevated Hx levels, only catabolism is increased in patients with
sickle cell anemia.
Abbreviations:
(heme) (iron protoporphyrin IX regardless of oxidation state), (Hx) (hemopexin), (AIP) (acute intermittent porphyria), (DMD) (Duchenne muscular dystrophy), (SCA) (sickle cell anemia), (NP) (idiopathic sensory neuropathy), (ALS) (amyotrophic lateral sclerosis), (NSM) (morphologically nonspecific myopathy), (MG) (myasthenia gravis), (PM) (polymyositis), (TCA) (trichloroacetic acid), (CPK) (creatinine phosphokinase), (t12) (half-life)To read this article in full you will need to make a payment
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Article info
Publication history
Accepted:
July 19,
1983
Received:
May 24,
1983
Footnotes
☆Work partially performed at Scripps Clinic and Research Foundation, La Jolla, Calif.
☆☆This work was supported by grants AM-30203 and RR-00833 from National Arthritis and Metabolic Diseases.
Identification
Copyright
© 1983 Published by Elsevier Inc.
