Heparin neutralizing activity and coronary artery disease.

It has been previously shown and confirmed in the present investigation that the disaggregation of adenosine diphosphate (ADP)-induced platelet aggregates occurs at a slow rate more frequently in the platelet-rich plasma (PRP) of men with coronary artery disease. ADP-induced platelet aggregation was studied in the citrated PRP of 32 men (21 with and 11 without coronary artery disease) to determine the relation between release of heparin neutralizing activity (HNA) from platelets and the rate of platelet diaggregation. Each of the five PRP with slow (less than 10 per cent) disaggregation were from men with coronary artery disease. Platelets from these five PRP released from 34 to 51 per cent of their content of HNA during ADP-induced aggregation in contrast to the 27 PRP with more rapid disaggregation, only three of which had a detectable release of HNA. Of the latter 27 PRP, 21 had a second phase of aggregation which usually reached a peak of light transmission less than that of the first phase. These data are consistent with (but do not prove) the hypothesis that HNA released during aggreation may be one of the factors tending to prevent disaggregation of ADP-induced platelet aggregates.