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.
Bond
H
H
Division of Human Development, The Medical School, St Mary's Hospital, University of Manchester, UK.
Baker
B
B
Boyd
R D H
RD
Cowley
E
E
Glazier
J D
JD
Jones
C J P
CJ
Sibley
C P
CP
Ward
B S
BS
Husain
S M
SM
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