Clotting Activity of Platelet Phospholipids in Rat and Man
SummaryThe 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.