AJP - Heart and Circulatory Physiology, Vol 251, Issue 4 800-H807, Copyright © 1986 by American Physiological Society
Clearance of human platelet factor 4 by liver and kidney: its alteration by heparin
B. Rucinski, L. C. Knight and S. Niewiarowski
Human 125I-labeled platelet factor 4 (PF4) injected into rabbits showed a
biphasic exponential pattern of disappearance from the circulation
[half-life of the fast components was 0.75 min, that of the slow components
was 20 min] that was not affected by a 1,000-fold excess of unlabeled PF4.
Heparin resulted in a single-compartment disappearance of 125I-labeled PF4
(half-life = 25-40 min). Five minutes after injection of 125I-labeled PF4
greater than 40% radioactivity had accumulated in the liver and 4% in the
kidney. At that time, accumulation of 125I-labeled beta-thromboglobulin
(beta-TG) in the organs was low, approximately 4% in the kidneys and less
than 3.0% in the liver. Nuclear imaging studies revealed rapid clearance of
131I-labeled PF4 from blood and its predominant accumulation in the liver.
The half-lives of 131I-labeled PF4 radioactivity in liver and kidney were
96 and 252 min, fitting a single-compartment model. 131I-labeled beta-TG
accumulated predominantly in the kidney. The half-lives of 131I-labeled
beta-TG radioactivity in the kidney and in the liver were 84 and 414 min.
Simultaneous or subsequent injection of heparin did not affect the
distribution of 131I-labeled beta-TG but caused partial loss of
131I-labeled PF4 radioactivity from the liver and accelerated its
appearance in the urinary bladder. Injection of heparin resulted in a
100-fold increase of excretion in the urine of 125I-labeled Pf4
precipitable by 10% trichloroacetic acid.(ABSTRACT TRUNCATED AT 250 WORDS)
