ADP and Retention of Platelets in Glass Bead Columns

Platelet retention is known to be dependent upon ADP, thought to be derived either from red cells by hemolysis in the glass bead columns or from the platelets themselves. In order to study this, the following experiments were done in blood from 8 healthy subjects and 11 patients with prosthetic heart valves: The whole blood content of adenine nucleotides was measured, the platelet retention in whole blood was determined by Hellem’s modified method, the degree of hemolysis provoked by passage of whole blood and EDTA-anticoagulated blood was estimated, and finally the liberation of adenine, nucleotides from EDTA-blood was measured. The wholeblood content of ADP was similar in the two groups of subjects, as was the degree of hemolysis caused by passage of blood through the columns, while platelet retention was low in blood from the ball-valve patients. The adenine nucleotides were liberated in the same proportions as hemoglobin, and ADP appeared in plasma in mean concentrations of 0.10 juM in both groups of subjects after passage of EDTA-blood through the columns. The results indicate that ADP in amounts necessary to induce platelet retention is derived from red cells. The reduced retention in ball-valve patients in spite of normal ADP-liberation is probably a result of trauma to the platelets inflicted by the prosthetic valve.

 

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