Effect of estrogen on platelet aggregation in guinea pigs.

This experiment was carried out to explore the effect of estrogen on platelet aggregation, using Hartly strain guinea pigs. For the in vivo experiments, estradiol benzoate 1 mg/kg or 4 mg/kg was injected into male guinea pigs to observe the effects of this drug on platelet aggregation. In vitro studies were performed by incubating platelet-rich plasma with estradiol benzoate for 30 minutes at 37 degrees C. Aggregation was induced by the addition of aggregating agents: adenosine diphosphate (ADP, lobster or rabbit muscle, Merck), and collagen (calf skin, Bio-Data). The change in transmittance at 660 nm was recorded using NKK HEMA TRACER 1, model PAT-4A (Nippon Denshi Kagaku Co., Japan). Our results revealed that a 1 mg/kg injection of estrogen had a statistically significant suppressive effect on both ADP and collagen-induced platelet aggregation. While in the group with the 4 mg/kg injection of estrogen, this suppressing effect was not significant. In vitro studies by incubating platelet-rich plasma with estradiol had no inhibitory effect on aggregation induced by both ADP and collagen.