Fractionation of platelets according to size: functional and biochemical characteristics
The functional and biochemical heterogeneity of platelets has been studied using graded differential centrifugation to fractionate human platelets according to size while maintaining their morphological and functional integrity as indicated by scanning electron microscopy and content of beta-thromboglobulin. Aggregation kinetics were studied by both optical and quenched-flow methods involving single-particle counting. Large platelets were significantly more sensitive to ADP, but aggregated less rapidly than small platelets. Thrombin exerted a similar influence. Large platelets were also enriched in surface sialic acid and sulfhydryl groups and in internal glycogen, ATP, ADP, calcium, cyclic AMP, malonaldehyde, and succinate cytochrome c reductase when compared to small platelets, even when normalized per unit volume. ADP caused a more rapid breakdown of cyclic AMP in small platelets. Potential aging relationships were tested by isotope studies in rats. /sup 75/Se-selenomethionine was incorporated in vivo at a similar rate into all fractions. Large platelets labeled with /sup 51/Cr disappeared from circulation linearly and had a longer mean lifespan than small platelets, which disappeared exponentially. This behavior supports independent aging of platelet populations of differing size. The data suggest a distinct heterogeneity in platelet function and fate, which could derive from protection of large platelets against excessive activation by Ca2+-regulated events.
- Research Organization:
- Univ. of Virginia, Charlottesville
- OSTI ID:
- 5429593
- Journal Information:
- Am. J. Hematol.; (United States), Vol. 1
- Country of Publication:
- United States
- Language:
- English
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AMP
ATP
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CALCIUM
CENTRIFUGATION
CHROMIUM 51
GLOBULINS
GLYCOGEN
IN VITRO
METHIONINE
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SCANNING ELECTRON MICROSCOPY
SELENIUM 75
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CARBOXYLIC ACIDS
CHROMIUM ISOTOPES
DAYS LIVING RADIOISOTOPES
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550201* - Biochemistry- Tracer Techniques