Adaptation of cardiovascular responses to repetitive umbilical cord occlusion in the late gestation ovine fetus
Green, L.R., Kawagoe, Y., Homan, J., White, S.E. and Richardson, B.S. (2001) Adaptation of cardiovascular responses to repetitive umbilical cord occlusion in the late gestation ovine fetus. Journal of Physiology, 535, (3), 879-888. (doi:10.1111/j.1469-7793.2001.t01-1-00879.x).
Full text not available from this repository.
1. The impact of repeated umbilical cord occlusion on the normal maturation of fetal heart rate (FHR) and mean arterial pressure (MAP) and the cardiovascular responses to successive umbilical cord occlusion was investigated over a 21 day period in the latter part of gestation.
2. Fifteen chronically instrumented sheep (control group n = 6; occlusion group n = 9) were studied for 21 days (113-133 days of gestation, term = 145 days) with umbilical cord occlusions (90 s duration) performed every 30 min for 1-4 h each day. On days 1, 9 and 18, FHR, FHR variation and MAP were monitored continuously and fetal arterial blood gases, pH and metabolites were measured at predetermined intervals. The baroreflex response to 75-100 μg phenylephrine (i.v.) was tested on days 1 and 18.
3. Basal FHR decreased (ΔFHR: control, 34.6 ± 3.6 beats min1; occlusion, 36.9 ± 2.7 beats min1) and MAP increased (ΔMAP: control, 3.1 ± 1.7 mmHg; occlusion, 5.2 ± 2.1 mmHg) to a similar extent in control and occlusion groups between days 1 and 21 of the study. There was a small decline in FHR variation over the 21 day study in occlusion, but not control, group fetuses.
4. The magnitude of the fall in FHR decreased and the rise in MAP increased, despite similar changes in blood gases in response to umbilical cord occlusion, over the course of the 21 day study. Despite a significant decline in the ratio of ΔFHR to ΔMAP on days 9 and 18 compared to day 1, there was no difference between control and occlusion groups in baroreflex sensitivity. However ΔFHR/ΔPO2, an index of chemoreceptor sensitivity, had decreased by day 9 and 18 compared to day 1.
5. The cardiovascular responses to umbilical cord occlusion are altered with repetitive occlusions during the latter part of gestation, with a decrease in ΔFHR/ΔMAP, which does not involve changes in baroreflex sensitivity, but may involve changes in chemoreceptor sensitivity. However, repeated umbilical cord occlusion appears to have no impact on baseline cardiovascular control since there was no change in the normal maturational decrease in FHR and rise in MAP.
|Subjects:||R Medicine > R Medicine (General)|
|Divisions:||University Structure - Pre August 2011 > School of Medicine > Developmental Origins of Health and Disease
|Date Deposited:||07 Apr 2006|
|Last Modified:||01 Jun 2011 11:18|
|Contributors:||Green, L.R. (Author)
Kawagoe, Y. (Author)
Homan, J. (Author)
White, S.E. (Author)
Richardson, B.S. (Author)
|Contact Email Address:||firstname.lastname@example.org|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
Actions (login required)