Platelet hyperaggregability, blood prostacyclin and dipyridamole

The relationship between the degradation of prostacyclin in blood and antiplatelet drug effects in patients with atherosclerosis

Blood and plasma from 109 patients with atherosclerosis and 70 healthy volunteers were tested to study the rate of prostacyclin (PGI2) hydrolysis. It has been reported that patients with atherosclerosis have the enhanced velocity of PGI2 degradation. The increase in the velocity was more marked in blood than in plasma. The significant negative correlation between antiaggregation effects of pentoxifylline, nifedipine, and dipyridamole and the velocity of PGI2 degradation in the patients was found. These data suggest that the increase of PGI2 biosynthesis by the drugs studied can enhance their antiaggregation effect if processes of PGI2 degradation in blood are not accelerated.

Glucose and erythrocyte ATP: distinctive effects of dipyridamole and of ticlopidine

This experiment suggests the following points: 1. Erythrocytes in control patients and in atherosclerosis patients seem to have a variable grade of affinity for adenosine and for plasma glucose. This variable grade seems to fix the level of the adenosine triphosphate (ATP) reserves and induces the erythrocytes' deformability. 2. The drop in the level of ATP reserves that induces the poor deformability of the erythrocytes in atherosclerosis patients would appear to be caused by two consecutive shortages: first a shortage that seems to be related to a deficiency of erythrocyte adenosine as the ATP shortage disappears with dipyridamole treatment and then a shortage induced by the lack of erythrocyte glucose and suppressed by the addition of ticlopidine to the dipyridamole treatment.