Impaired red blood cell deformability after oral administration of aspirin in man

The effect of aspirin on red blood cell (RBC) deformability was studied in nine healthy male volunteers. They received 1.5 g aspirin daily in divided doses for three days and RBC deformability was measured before and two hours after the last dose of aspirin. Measurements were repeated seven and fourteen days after the last dose in five of the nine subjects. Red blood cell deformability was significantly (P less than 0.01) decreased 2 hours after aspirin and the effect persisted for seven days through by fourteen days after aspirin values had returned to pre-aspirin control levels. Direct incubations of RBC's with aspirin (300 mg/ml) in vitro had no effect on RBC deformability. These findings are consistent with a role of endogenous epoprostenol (prostacyclin) in regulating RBC deformability in vivo.