Biology of Reproduction, Vol 23, 553-557, Copyright © 1980 by Society for the Study of Reproduction

Effect of Epsilon Amino Caproic Acid, a Fibrinolytic Inhibitor, on Implantation and Fetal Viability in the Rat

¹ Department of Gynecology and Obstetrics, The Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205

In vitro evidence suggests that fibrinolytic activity is involved in the implantation process. In vivo experiments were performed in rats to determine if fetal development can be prevented by epsilon amino caproic acid (EACA), a fibrinolytic inhibitor. Timed pregnant rats were laparotomized on various days of pregnancy, and EACA or control injections were made directly into a uterine horn. Animals were autopsied on Day 15 of pregnancy when implantation and fetal viability rates were determined. Intraluminal EACA did not affect implantation rate, but fetal viability was adversely affected when 3 mg EACA were injected on Day 6. This effect was doserelated and was partially reversed by simultaneous injection of plasmin. No effect was observed on Day 3, 7, or 8. The effect on Days 4 and 5 could not be tested because sham injections alone caused a high resorption rate. Subcutaneous injections, as high as 60 mg daily from Days 3 to 10, did not affect fetal viability. The experiments support the hypothesis that fibrinolytic activity around the time of implantation is important for maintenance of pregnancy.

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ACKNOWLEDGMENTS The authors thank Nancy Baros and Barbara Widerman for their expert technical assistance. Appreciation is expressed to Susan Scheper for her excellent assistance in preparation of the manuscript. Supported by USAID CSD-3627.