Uterine oxygen uptake in the pregnant Pygmy goat

The diffusion equilibrium method was used to measure uterine blood flow (Qut) and oxygen consumption (VutO2) of 7 Pygmy goats in the last third of pregnancy. VutO2 was 9.3 +/- 1.3 (mean +/- SEM) ml.min-1.kg-1 weight of the uterus and its contents: the placenta, fetus and fetal membranes. This O2 requirement was provided by a high blood flow (349 +/- 48 ml.min-1.kg-1) and a narrow arteriovenous difference (2.4 +/- 0.1 vol%) across the uterus. Maternal arterial O2 content (CaO2) was varied by incurring chronic anemia in 3 animals. CaO2 over the range 6.5 - 12.8 vol% did not affect uterine blood flow or the arteriovenous oxygen content difference across the uterus. Weight specific (ml.min-1.kg-1) VutO2 did not differ in animals whose total uterine weights varied over a wide range and uterine vein oxygen tension and content did not fall prior to delivery. We conclude that the absolute uterine blood flow varies over a wide range to meet the requirements of the uterine contents.