Summary
The clotting activity of man and rat platelet phospholipid fractions separated by
bi-dimensional TLC, resuspended in Tyrode by sonication, was studied in the recalcification
(manual) and in the Stypven (recalcification plus Russell’s viper venom) clotting
time (determined in a coagulometer). Phosphatidyl serine was the most active fraction
to shorten the two clotting tests utilized, in both rat and man, but it was much more
effective in the Stypven time. The phosphatidyl ethanolamine was the second most active
fraction, in the Stypven time; this fraction was almost as active as phosphatidyl
serine in both animal species. The other fractions studied (phosphatidyl inositol,
phosphatidyl choline and sphingomyelin) were sligthly active or not active, depending
on the experimental conditions.
The clotting activity of platelet phosphatidyl serine from rat, at concentrations
corresponding to platelet counts from 1 to 10 ( X105), was much smaller than this of the disrupted (sonicated) platelets from which it
originated. However, the clotting activity of sonicated platelets could be completely
reproduced, either at each concentration studied (Stypven time) or at a concentration
corresponding to lOxlO5 platelets (recalcification time), by adding to phosphatidyl serine the other four
phospholipid fractions (phosphatidyl inositol, phosphatidyl ethanolamine, phosphatidyl
choline, sphingomyelin) dispersed in a homogeneous way by sonication.
The feeding of a butter-rich diet to rats considerably increased the activity of each
of the platelet phospholipid fractions in the two clotting tests carried out.
