Expression of angiotensin-converting enzyme in human placenta and its physiologic role in the fetal circulation.
OBJECTIVE
To clarify the physiologic function of angiotensin-converting enzyme (EC 3.4.15.1) in the human placenta.


METHODS
The concentrations of angiotensin I and angiotensin II were measured in the umbilical artery and vein. In addition, the expression of angiotensin-converting enzyme messenger RNA (mRNA) and its activity in the human placenta were studied. The amount of angiotensin-converting enzyme mRNA was measured by Northern blot hybridization with specific human complementary DNA.


RESULTS
The mean (+/- standard deviation) level of angiotensin I was significantly higher in the umbilical artery than in the umbilical vein (1044.5 +/- 626.5 versus 796.5 +/- 372.8 pg/mL; P < .05). In contrast, the mean level of angiotensin II was significantly lower in the umbilical artery than in the umbilical vein (97.3 +/- 102.9 versus 129.3 +/- 110.3 pg/mL; P < .05). Angiotensin-converting enzyme mRNA was detected in the human placenta at 4.5 and 3.9 kilobases. The amount of angiotensin-converting enzyme mRNA increased over the course of pregnancy but decreased near term, whereas angiotensin-converting enzyme activity in the human placenta continued to increase from the first trimester to term.


CONCLUSIONS
The placenta appears to contribute to the conversion of angiotensin I to angiotensin II in the fetal circulation.
Yagami
H
H
Department of Obstetrics and Gynecology, Nagoya University, Japan.
Kurauchi
O
O
Murata
Y
Y
Okamoto
T
T
Mizutani
S
S
Tomoda
Y
Y
D000803:Angiotensin I / Q000097:blood; D000804:Angiotensin II / Q000097:blood; D015152:Blotting, Northern; D005260:Female; D005333:Fetus / Q000098:blood supply*; D015870:Gene Expression; D006801:Humans; D007703:Peptidyl-Dipeptidase A / Q000096:biosynthesis / Q000502:physiology*; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy / Q000097:blood / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics
D012333:RNA, Messenger; D000804:Angiotensin II; D000803:Angiotensin I; D007703:Peptidyl-Dipeptidase A