Artificial perfusion of the fetal circulation of the in situ mouse placenta: methodology and validation.
Here we present methodology and validation (including measurement of unidirectional maternofetal clearance (Kmf) of (45)Ca and (14)C-mannitol) for in situ perfusion of the mouse placenta. On day 18 of gestation (term=19 days) mice were anaesthetised and the uterus delivered into a saline bath (40 degrees C). A fetus was selected, the umbilical artery and vein catheterised and perfused with Krebs Ringer (pH 7.4) at 60 microl/min. (45)Ca/(14)C-mannitol (2 microCi/5 microCi in 50 microl saline) was injected via maternal tail vein. Perfusate samples were collected every 5 min for 45 min. Maternal carotid artery pressure was monitored throughout perfusion. A terminal maternal cardiac blood sample was taken and analysed. Placentas were immersion fixed and processed for electron microscopy. Kmf for (45)Ca and (14)C-mannitol was calculated as perfusate [(45)Ca or (14)C-mannitol] x perfusion rate/maternal plasma [(45)Ca or (14)C-mannitol]xplacental weight. Maternal cardiac blood chemistry at termination (n=8-15, mean+/-SEM) was as follows: pH 7.153+/-0.016, PCO(2) 45.48+/-2.06 mmHg, PO(2) 66.47+/-7.10 mmHg, Na(+) 151.4+/-1.2 mmol/l, K(+) 5.54+/-0.17 mmol/l, Ca(2+) 1.15+/-0.03 mmol/l, glucose 7.2+/-0.5 mmol/l, and lactate 1.76+/-0.77 mmol/l. A successful 45 min perfusion in which perfusate recovery was >95% occurred in >50% of animals. Perfusion did not alter placental morphology or carotid pressure. Kmf (microl/min/g placenta) for (45)Ca (66.0+/-8.4 (n=7)) was significantly higher than Kmf for (14)C-mannitol (20.0+/-2.4 (n=5)) (p<0.01). These data demonstrate physiological perfusion of the mouse placenta in situ and its usefulness for measurement of solute transfer.
Division of Human Development, The Medical School, St Mary's Hospital, University of Manchester, UK.
H
H
Bond
B
B
Baker
R D H
RD
Boyd
E
E
Cowley
J D
JD
Glazier
C J P
CJ
Jones
C P
CP
Sibley
B S
BS
Ward
S M
SM
Husain
D000818:Animals; D001692:Biological Transport; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005333:Fetus / Q000098:blood supply*; D006706:Homeostasis; D008297:Male; D008431:Maternal-Fetal Exchange / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D008854:Microscopy, Electron; D010477:Perfusion / Q000379:methods*; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D011865:Radioisotope Dilution Technique; D013997:Time Factors