In the fetus, there is a redistribution of cardiac output in response to acute hypoxemia, to maintain perfusion of key organs including the brain, heart and adrenal glands. There may be a similar redistribution of cardiac output in the chronically hypoxemic, intrauterine growth restricted (IUGR) fetus. Surgical removal of uterine caruncles in non-pregnant ewe results in the restriction of placental growth (PR) and IUGR. Vascular catheters were implanted in 7 Control and 6 PR fetal sheep and blood flow to organs was determined using microspheres. Placental and fetal weight was significantly reduced in the PR group. Despite an increase in the relative brain weight in the PR group, there was no difference in blood flow to the brain between the groups, although PR fetuses had higher blood flow to the temporal lobe. Adrenal blood flow was significantly higher in PR fetuses and there was a direct relationship between mean gestational PaO2 and blood flow to the adrenal gland. There was no change in blood flow, but a decrease in oxygen and glucose delivery to the heart in the PR fetuses. In another group, there was a decrease in femoral artery blood flow in PR compared to Controls and this may support blood flow changes to the adrenal and temporal lobe. In contrast to the response to acute hypoxemia, these data show that there is a redistribution of blood flow to the adrenals and temporal lobe, but not the heart or whole brain, in chronically hypoxemic PR fetuses in late gestation.
- developmental programming
- Copyright © 2014, American Journal of Physiology - Regulatory, Integrative and Comparative Physiology