Comparison of the effect of heparin and citrate on platelet aggregation.

When whole blood was passed through a column of glass beads, heparinized and native blood gave similar results. With citrated blood far fewer platelets were lost on the column. Thus citrate inhibits this test and heparin has no effect.Platelet-rich plasma (PRP) was prepared from citrated and heparinized blood and the responses in a number of aggregation tests were compared. With added adenosine diphosphate and adrenaline (first wave), the response in heparin PRP was greater than that in citrate PRP and was proportional to the amount of free calcium ions. With added collagen and adrenaline (second wave) the response was worse in heparin than in citrate platelet-rich plasma. It is concluded that heparin has no effect on the adhesive forces but inhibits the release mechanism. This may be of therapeutic importance.