Endothelin receptor A antagonism prevents hypoxia-induced intrauterine growth restriction in the rat.

OBJECTIVE

Our purpose was to investigate the hypothesis that endothelin plays a critical role in maternal hypoxia-induced intrauterine growth restriction.

STUDY DESIGN

Chronic indwelling venous and arterial catheters were placed on day 17 of a 22-day gestation in timed-pregnant Sprague-Dawley rats. Twelve rats were infused with saline solution and 12 with 6 mg/kg per day FR139317, an endothelin receptor A-specific antagonist. For gestational days 18 to 21 half the rats in each infusion group were housed in a normoxic environment and the other half in a hypoxic (14% oxygen) environment. On day 21 an arterial blood gas level was determined, the rats were then anesthetized, and a hysterotomy was performed. The weight of each pup and its corresponding placenta was recorded. Statistical significance was determined by analysis of variance.

RESULTS

Among the rats receiving saline solution infusions, fetal weights were 20% less and placental weights were 11% less for those housed in a hypoxic environment compared with those housed in a normoxic environment (p < 0.003). Among the rats receiving FR139317 infusions, fetal and placental weights were not significantly different for those in a hypoxic environment compared with those in a normoxic environment. The fetal and placental weights for the rats receiving FR139317 infusion in hypoxic or normoxic environments were similar to those receiving saline solution in a normoxic environment.

CONCLUSIONS

Endothelin plays a critical role in hypoxia-induced intrauterine growth restriction. Infusion of an endothelin antagonist prevents the intrauterine growth restriction caused by chronic hypoxia.