IS UTERINE BLOOD-FLOW CONTROLLED LOCALLY OR SYSTEMICALLY IN THE PREGNANT RABBIT

OBJECTIVE: We tested the hypothesis that uterine blood flow is regulat ed by systemic circulating factors. The alternative hypothesis is that uterine blood flow is regulated by local factors. STUDY DESIGN: Adult female New Zealand White rabbits were subjected to a unilateral tubal ligation and thereafter allowed to become pregnant (n = 9). A group o f nonpregnant one-tube-ligated animals served as controls (n = 8). On day 21 of gestation uterine blood flow in the pregnant and nonpregnant uterine horns were measured with 15 mum microspheres. The concentrati on of prostaglandin E2 metabolites were measured in blood from the ute rine veins and from the arterial circulation. RESULTS: Absolute uterin e blood flow in the pregnant uterine horn was 12.9 +/- 4.7 versus 5.2 +/- 1.4 ml in the nonpregnant horn (p < 0.05). However, when expressed by blood flow per gram of tissue they were not different (p > 0.1). T he uterine blood flow for the nonpregnant uterine horn in the pregnant animals was the same as that of the horns from nonpregnant animals. T he level of prostaglandin E metabolites was greater in the uterine vei n draining the pregnant horn compared to the nonpregnant horn (p < 0.0 5). CONCLUSION: These data support the conclusion that the increase in uterine blood flow observed during pregnancy is controlled largely by local factors induced by pregnancy.