Summary
ADP-induced platelet aggregation in citrated platelet rich plasma (CPRP) was examined
using a photoelectric system. To exclude a variation in intensities of platelet aggregation
in repeated measurements and to compare intensities of different samples, the maximum
deflection of the optical density of CPRP induced by adding ADP solution was divided
by a deflection of the optical density of the platelet free plasma and its value,
shown as a percentage, was defined as an intensity of ADP-induced platelet aggregation.
In this method, the linearity was found in the dose response curve of the platelet
aggregation induced by 10−6, 3 × 10−6 and 10−5 molar of ADP with statistical significance. These variation coefficients were less
than 5% in the responses induced by the higher doses of ADP. Changes in the ADP-induced
platelet aggregation after a Master’s two step test were examined in 13 patients with
angina pectoris 3 h after oral administration of placebo or 1 g of pyridinolcarbamate.
Under placebo pretreatment, an enhancement of platelet aggregation was observed 1
min after the exercise test with statistical significance (P < 0.01 ∼ 0.05). In the
cases of the same subjects pretreated with pyridinolcarbamate, such change was not
observed at any time. Using a parallel line assay, an inhibitory effect of pyridinolcarbamate
against enhancement of ADP-induced platelet aggregation after the exercise was also
recognized with statistical significance (P < 0.01). In the 10 healthy volunteers,
there was no statistically significant enhancement of ADP-induced platelet aggregation
using any concentration of ADP 1 to 10 min after the exercise test.
