Uterine oxygen uptake in the pregnant pygmy goat

The diffusion equilibrium method was used to measure uterine blood flow (Q̇ut) and oxygen consumption (V̇utO 2) of 7 Pygmy goats in the last third of pregnancy. V̇utO 2 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 O 2 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 O 2 content (Ca O 2 ) was varied by incurring chronic anemia in 3 animals. Ca O 2 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) V̇ut O 2 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.