The effect of fetal acidemia on fetal-placental vascular tone and production of the inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha.
OBJECTIVE
Our purpose was to determine the effects of fetal acidemia on placental vascular tone and production of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha).


METHODS
With use of an ex vivo placental perfusion model, the maternal and fetal circulation of two cotyledons from five human placentas were perfused for 4 hours. The fetal circulation of one cotyledon was perfused with acidemic (pH 6.90) Hanks' balanced salt solution (HBSS), whereas the fetal circulation of the other cotyledon was perfused with physiologic (pH 7.35) HBSS. Fetal venous effluents were collected hourly, and IL-6 and TNF-alpha concentrations were determined by enzyme-linked immunosorbent assay. Cotyledon perfusion pressures were recorded every 10 minutes. Paired t tests were used to compare differences in cytokine production and perfusion pressure between the cotyledons.


RESULTS
Fetal-placental vascular perfusion pressure was consistently reduced from baseline under acidemic, but not physiologic, conditions with statistical significance achieved from 20 minutes onward (P <.05). IL-6 and TNF-alpha increased exponentially over time for both conditions (P <.05). There was no difference in cytokine production when acidemic conditions were compared with physiologic conditions (P <.05).


CONCLUSIONS
Fetal-placental vasodilation may be a compensatory mechanism to improve acidemic conditions. Unlike fetal hypoperfusion or fetal hyperoxia, fetal acidemia does not result in elevated placental cytokine levels.
Pierce
Brian T
BT
Division of Maternal-Fetal Medicine, Madigan Army Medical Center, Ft. Lewis, WA, USA.
Napolitano
Peter G
PG
Pierce
Lisa M
LM
Kovac
Christine
C
Hume
Roderick F
RF
Calhoun
Byron C
BC
D000143:Acids / Q000097:blood*; D005260:Female; D005312:Fetal Blood; D005333:Fetus / Q000098:blood supply*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000096:biosynthesis*; D009994:Osmolar Concentration; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D012016:Reference Values; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D014664:Vasodilation; D014666:Vasomotor System / Q000503:physiopathology*
D000143:Acids; D018836:Inflammation Mediators; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha