Fetal in vivo continuous cardiovascular function during chronic hypoxia
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Allison, B., Brain, K., Niu, Y., Kane, A., Herrera, E., Thakor, A., Botting, K., et al. (2016). Fetal in vivo continuous cardiovascular function during chronic hypoxia. 594 1247-1264. https://doi.org/10.1113/JP271091
Although the fetal cardiovascular defence to acute hypoxia and the physiology underlying it have been established for decades, how the fetal cardiovascular system responds to chronic hypoxia has been comparatively understudied. We designed and created isobaric hypoxic chambers able to maintain pregnant sheep for prolonged periods of gestation under controlled significant (10% O2) hypoxia, yielding fetal mean PaO2 levels (11.5±0.6 mmHg) similar to those measured in human fetuses of hypoxic pregnancy. We also created a wireless data acquisition system able to record fetal blood flow signals in addition to fetal blood pressure and heart rate from free moving ewes as the hypoxic pregnancy is developing. We determined in vivo longitudinal changes in fetal cardiovascular function including parallel measurement of fetal carotid and femoral blood flow and oxygen and glucose delivery during the last third of gestation. The ratio of oxygen (from 2.7±0.2 to 3.8±0.8; P<0.05) and of glucose (from 2.3±0.1 to 3.3±0.6; P<0.05) delivery to the fetal carotid, relative to the fetal femoral circulation increased during and shortly after the period of chronic hypoxia. In contrast, oxygen and glucose delivery remained unchanged from baseline in normoxic fetuses. Fetal plasma urate concentration increased significantly during chronic hypoxia but not during normoxia (∆: 4.8±1.6 vs. 0.5±1.4 µmol.L^-1, P<0.0.05). The data support the hypotheses tested and show persisting redistribution of substrate delivery away from peripheral and towards essential circulations in the chronically hypoxic fetus, associated with increases in xanthine oxidase-derived ROS.
cerebral blood flow, femoral blood flow, oxygen delivery, glucose delivery, placental insufficiency, preeclampsia
This work was supported by the British Heart Foundation.
British Heart Foundation (RG/06/006/22028)
British Heart Foundation (PG/10/99/28656)
British Heart Foundation (RG/11/16/29260)
British Heart Foundation (FS/12/74/29778)
British Heart Foundation (PG/14/5/30547)
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External DOI: https://doi.org/10.1113/JP271091
This record's URL: https://www.repository.cam.ac.uk/handle/1810/250600
Attribution 4.0 International
Licence URL: http://creativecommons.org/licenses/by/4.0/