LACK OF RESPONSE OF BRAIN AND ADRENAL BLOOD FLOW TO HYPOXEMIA IN THE FETAL LLAMA

Abstract

The fetus of sheep a species that evolved in lowlands, responds to hypoxemia (H) by maintaining cardiac output and umbilical-blood flow, increasing heart, brain and adrenal blood flow and decreasing it to other organs. The response to H of the fetus of the llama, that has evolved in high altitudes, is not fully understood. We postulate that the systemic responses to H in the fetal llama are less marked and that the main adaptation occurs at the cellular and tissue levels. Our aim was to compare cardiac output and its distribution at 0 min (B) and after 20 min of fetal H (22-27% Sathb and 3-6 m102/dl in descending aorta) in 8 fetal sheep and 8 fetal llamas at 0.8 gestation. The results (x̄ + SEM) were: Under basal and hypoxemic conditions fetal llamas have lower blood flows than fetal sheep. Moreover, there is no change in brain and adrenal blood flows during hypoxemia. These results suggest that one of the main adaptations to hypoxemia in fetal llamas is an increase in cellular oxygen extraction. Grant Fondecyt 89-1080.