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B Lages, MC Scrutton, H Holmsen, HJ Day and HJ Weiss
Platelets from nine patients with storage pool disease (SPD) and from ten
control subjects were isolated by gel filtration into a suspension medium
permitting the direct determination of platelet Mg-2+, Ca-2+, and K+
levels. The total intracellular levels of ATP and ADP, as well as the
incorporation patterns of 14-C-adenine into the metabolic nucleotide pool,
were also determined in these platelet suspensions. The gel-filtered
platelets (GFP) from SPD patients exhibited slightly lowered levels of ATP
and substantially reduced amounts of ADP, in agreement with previous
studies using PRP suspensions. Diminished aggregation responses to ADP,
epinephrine, and to collagen in particular, similar to those observed
previously in PRP, were obtained in GFP from SPD patients. However, GFP
from the patients exhibited more variable aggregation responses to addition
of ADP and epinephrine than did GFP from the control subjects. Increases in
the extent of radioactive hypoxanthine formation, observed previously in
normal platelets as a result of isolation into the suspension medium used
in these studies, were significantly reduced in the GFP from SPD patients.
The levels of platelet Mg-2+ and K+ determined in GFP from the patients
were not significantly different from the levels of these ions in GFP from
control subjects. However, substantial reductions in platelet Ca- 2+ were
found in the SPD platelets. A strong correlation was obtained between this
reduction in platelet Ca-2+ and the reduction in ADP in these platelets. No
such correlation was apparent between the ATP and Ca-2+ deficiencies. These
results suggest that a major portion of platelet Ca-2+ may be located in
the dense granules and support previous hypotheses that granular ADP and/or
Ca-2+ may play a role in the release reaction. The finding of normal levels
of platelet Mg-2+ and K+ in SPD platelets, however, suggests that these
latter ions are not located in the dense granules.
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| Copyright © 1975 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||