Appearance of Platelet-Clumping Substance after Acidification of Human Plasma

Abstract

The pH values of heparinized plasma from seven healthy volunteers were from 7.72 to 7.81. The average pH and standard error was 7.76±0.01. These plasma samples did not show platelet-clumping activity. Immediately after acidification of plasma, the platelet-clumping substance appeared in six of the all seven plasma samples at pH values from 6.86 to 5.82 at room temperature. The range of the upper pH value, in which the clumping substance was observed, was 6.866.20 (6.54±0.10 in average) and the lower range 6.48-5.82 (6.18±0.09 in average). The platelet-clumping substance clumped not only washed platelets suspended in the saline but also unwashed platelets in CPRP equally. The clumping substance did not appear in the citrated or EDTA plasma. On the contrary, the clumping activity did not disappear in the acidified heparinized plasma after the addition of citrate, oxalate or EDTA.