This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Morgan, T. Articles by Ward, K. Search for Related Content PubMed PubMed Citation Articles by Morgan, T. Articles by Ward, K.

(Hypertension. 1998;32:683-687.)
© 1998 American Heart Association, Inc.

Scientific Contributions

Human Spiral Artery Renin-Angiotensin System

Terry Morgan; Catherine Craven; ; Kenneth Ward

From the Departments of Human Genetics (T.M., K.W.) and Obstetrics and Gynecology (C.C., K.W.), University of Utah Health Sciences Center, Salt Lake City.

	Abstract

Top Abstract Introduction Methods Results Discussion References

 
Abstract—Pregnancy induces uterine spiral arteries to remodel into dilated uteroplacental vessels by an unknown mechanism called "physiological change." In women who develop preeclampsia, however, many spiral arteries remain unchanged or develop medial hyperplasia and atherosis. We recently demonstrated that angiotensinogen is expressed by remodeling spiral arteries in first-trimester decidua. We hypothesize that a local spiral artery renin-angiotensin system mediates pregnancy-induced remodeling of these vessels. In this study we tested for expression of renin, angiotensin-converting enzyme, and angiotensin II type 1 receptor genes in the first-trimester uterus using reverse-transcription polymerase chain reaction. Expression was localized by in situ hybridization and immunohistochemistry. Renin, angiotensin-converting enzyme, and the angiotensin II type 1 receptor are all expressed in and around remodeling spiral arteries. These observations suggest that a local spiral artery renin-angiotensin system may play a role in pregnancy-induced remodeling of these vessels. Elevated angiotensinogen expression in women homozygous for the A(-6) variant in the angiotensinogen promoter may promote abnormal remodeling, whereas relatively lower levels in women homozygous for G(-6) may permit enough normal remodeling to protect these women from preeclampsia.

Key Words: renin-angiotensin system • arteries • preeclampsia • human

	Introduction

Top Abstract Introduction Methods Results Discussion References

 
Pregnancy induces the uterine spiral arteries to remodel into dilated uteroplacental vessels by an unknown mechanism called "physiological change."¹ In women who develop preeclampsia, however, spiral arteries frequently remain unchanged or develop medial hyperplasia and atherosis.² The factors mediating spiral artery remodeling and the underlying mechanisms leading to abnormal remodeling are unknown.

We have recently shown that the earliest stages of spiral artery remodeling are mediated by maternal factors.³ Our data suggest that maternal angiotensinogen (AGT) expression in spiral artery smooth muscle cells may play a role in pregnancy-induced remodeling of these vessels.⁴ A growing body of evidence supports the existence of a tissue-based renin-angiotensin system (RAS) in blood vessels,^{4 5 6 7 8 9} which appears to play a role in the vascular response to injury, sheer stress, and vasoactive hormones.¹⁰

There are a number of ways to test for the presence of a local RAS. The most convincing evidence is de novo expression.⁹ In this study we tested for renin, angiotensin-converting enzyme (ACE), and angiotensin II type 1 receptor (AT₁) expression in the first-trimester uterus using reverse-transcription–polymerase chain reaction (RT-PCR). We localized expression of these components by in situ hybridization and immunohistochemistry.

	Methods

Top Abstract Introduction Methods Results Discussion References

 
Samples
Using a protocol approved by the University of Utah Institutional Review Board, we obtained products of conception from normal first- and second-trimester pregnancies after elective termination. We collected 60 samples of maternal decidua (5 to 13 weeks of gestation). We also collected fetal kidney, heart, and placental villi samples (19 weeks of gestation) to be used as positive controls for renin, ACE, and AT₁ expression.^{11 12 13} Each tissue sample was split into 2 pieces. One portion was immediately frozen in liquid nitrogen to preserve the RNA, and the other was fixed in cold buffered formalin for in situ studies and for routine histology.

Nucleic Acid Preparation
Total RNA was prepared from frozen maternal decidua, fetal kidney, heart, and villi using Tri-Reagent (Molecular Research Center Inc) according to manufacturer's instructions.¹⁴

Reverse Transcription–PCR
We selected primers designed from renin exon 2 (253 to 280 bp), 5'-TGG AGC CAA CCC ATG AAG AGG CTG ACA-3', and from exon 5 (2441 to 2414 bp), 5'-GGC ATC TCC GTG ACC TCT CCA AAC ATC-3'. These primers flank multiple introns¹⁵ and do not amplify genomic DNA. ACE primers were designed from exon 3 (486 to 513 bp), 5'-AGG TCT GCC TCC CCA ACA AGA CTG CCA-3', and from exons 5 and 6 (810 to 783 bp), 5'-CAG TGC GCG GCG GAC GAA GGC ATG GAG-3'. These primers also flank multiple introns¹⁶ and do not amplify genomic DNA. AT₁ primers were designed from the AT₁ gene¹⁷ as follows: 140 to 167 bp, 5'-CAG CTT GGT GGT GAT AGT CAT TTA CTT-3' and 480 to 453 bp, 5'-CTG GCC AAG CCT GCC AGC AGC CAA ATG-3'. In each experiment, 300 ng of total RNA from fetal kidney, heart, and villi served as positive controls. Water blanks were used to detect reagent contamination. Total RNA (300 ng) from decidual samples was used as a template for reverse transcription. Reverse transcription was performed as follows: RNA samples were mixed with 5.0 U rTth polymerase (Perkin-Elmer Corp), 0.75 µmol/L "downstream" primer, 200 µmol/L dNTP, 1 mmol/L MnCl₂, and 1x rTth reverse transcriptase buffer (Perkin-Elmer) in a total volume of 20 µL. The samples were incubated for 30 minutes at 65^° to reverse-transcribe mRNA into cDNA, then PCR was amplified as follows: The 20 µL reverse transcription reaction was expanded to 100 µL by adding "upstream" primer (final concentration 0.15 µmol/L), MgCl₂ (final concentration 2.0 mmol/L), and chelating buffer (final concentration 0.8x) to chelate the Mn²⁺. The cDNA was amplified using a GeneAmp 9600 thermocycler (Perkin-Elmer) as follows: 1 minute at 94^°, then 35 cycles of 10 seconds at 94^° and 15 seconds at 60^°. RT-PCR products were visualized by ethidium bromide staining after electrophoretic fractionation through 3% 3:1 NuSieve-Seakem agarose gels. RT-PCR products from 1 decidual sample were also sequenced to confirm reaction specificity.

Cryosectioning
Tissue samples from fetal kidney and maternal decidua were fixed for 2 hours in 4% paraformaldehyde (pH 7.4) at 4°C and then submerged overnight in 0.1% DEPC-treated 15% sucrose solution (PBS, pH 7.4) at 4°C. These samples were then frozen in liquid nitrogen. Samples were sectioned, fixed in 4% paraformaldehyde (pH 7.4) for 2 hours at 4°C, and rinsed in PBS and then proteinase K–digested (6 µg/mL in PBS) for 20 minutes, rinsed, and refixed for 15 minutes in 4% paraformaldehyde at room temperature. They were then dehydrated by submersion in 50%, 75%, and 100% ethanol and stored at -70°C.

Riboprobe Preparation
The renin RT-PCR product described above was cloned into the pSPT19 plasmid–containing promoters for in vitro transcription (Boehringer Mannheim Biochemicals). The pSPT19-REN clone was sequenced to confirm orientation and integrity. The plasmid was then linearized either upstream or downstream from the insert, phenol-extracted, and transcribed in the presence of digoxigenin-labeled UTP to generate either a sense or antisense digoxigenin-labeled riboprobe (Dig-RNA labeling kit using SP6 or T7 polymerase, Boehringer Mannheim Biochemicals).

In Situ Hybridization
Cryosections were covered by 20 µL of heat-denatured hybridization solution (50% vol/vol formamide, 4x SSC, 1x Denhardt's, 0.5 mg/mL salmon sperm DNA, 0.25 mg/mL yeast tRNA, 10% dextran sulfate, and 200 ng/mL riboprobe), placed on coverslips, and incubated overnight at 50°C in a humid chamber. The slides were washed for 5 minutes at room temperature in 2x SSC, followed by 1 minute in STE buffer (500 mmol/L NaCl, 1 mmol/L EDTA, 20 mmol/L Tris-HCl, pH 7.5). They were then treated with RNAse A (40 µg/mL) for 30 minutes at 37°C to degrade unbound probe and reduce background signal, followed by a "hot wash" in 2x SSC/50% formamide for 5 minutes at 50°C. Finally, sections were washed at room temperature for 5 minutes in 1x SSC, then 5 minutes in 0.5x SSC. Negative control slides were either hybridized with renin sense probe or pretreated with RNAse A.

Immunodetection of Riboprobe
Immunodetection of the digoxigenin-labeled riboprobe was performed using an alkaline phosphatase–conjugated anti-digoxigenin antibody (Boehringer Mannheim Biochemicals). The riboprobe antibody complex was visualized by adding the alkaline phosphatase substrates nitro blue tetrazolium and 5-bromo-4-chloro-3-indoyl phosphate. Sections were counterstained with eosin and photographed (Optiphot-2, Nikon Inc).

Immunohistochemistry
To investigate the location of ACE expression in human decidua, we stained paraffin-embedded sections of decidual samples and fetal heart positive control for ACE protein using a monoclonal anti-ACE IgM antibody (1:1000, QED Bioscience Inc). Purified mouse IgM was used as a negative control (Dako Co).

To investigate the location of AT₁ expression in human decidua, we stained paraffin-embedded sections of first-trimester decidua, placenta, and fetal kidney positive controls for AT₁ protein using a polyclonal antibody against rat AT₁ receptor (1:800, Chemicon International Inc). This antibody does not recognize any protein in PC12 cells, which are known to predominantly express AT₂ receptors. Immunostaining with purified rabbit immunoglobulins (1:800) served as a negative control (Dako Co).

To determine whether the cells expressing renin mRNA were spiral artery smooth muscle cells, we stained serial sections of the tissue used for in situ hybridization for -smooth muscle cell actin or von Willebrand factor (1:50 and 1:200, respectively; Dako Co).

Immunostaining was performed according to routine methods as suggested by the manufacturer (Dako). Briefly, sections were blocked with 3% blocking reagent (Boehringer), incubated with the appropriate primary antibody, and then incubated with biotinylated anti-mouse/anti-rabbit secondary antibodies (Dako). Sections were then labeled with streptavidin conjugated to horseradish peroxidase and visualized with 3-amino-9-ethyl-carbazole (Sigma Chemical Co), counterstained with Mayer's hematoxylin, and photographed.

	Results

Top Abstract Introduction Methods Results Discussion References

 
RAS Components Expressed in Maternal Decidua
All decidual extracts tested by RT-PCR yielded renin-, ACE-, and AT₁-specific products of expected size (Figure 1) and sequence (data not shown). We have previously shown local expression of AGT in this tissue⁴ ; therefore, de novo expression of all RAS components in human decidua is consistent with the presence of a local RAS.⁹ Although expression levels of renin and AT₁ are relatively consistent from 5 to 13 weeks of gestation, ACE expression levels appear to decline after 10 weeks of gestation (Figure 1).

View larger version (80K): [in this window] [in a new window]   Figure 1. RAS components are expressed in maternal decidua. RT-PCR amplification of total RNA (300 ng) prepared from fetal kidney (K), heart (H), and placenta (P) (19 weeks of gestation) and maternal decidua (M; 5, 7, 10, and 13 weeks of gestation). Water (W) served as the negative control. Renin, ACE, and AT1 RT-PCR products are expected size (390, 320, and 340 bp, respectively) and sequence (data not shown).

Renin Expression Localized to Vascular Smooth Muscle Cells
As expected, in situ hybridization studies localized expression of the renin transcript to fetal kidney afferent arteriole smooth muscle cells.¹¹ Concurrent experiments performed in first-trimester decidua localized renin transcript to the vessel wall of decidual veins and unremodeled spiral arteries (Figure 2A). Positive cells were confirmed to be smooth muscle cells by the presence of -smooth muscle cell actin immunostaining in serial sections. Negative controls, including RNAse-digested tissue or sections hybridized with the renin sense probe, were negative (Figure 2B).

View larger version (120K): [in this window] [in a new window]   Figure 2. Localization of RAS components. A, In situ hybridization studies using digoxigenin-labeled cRNA probe localized expression of the renin transcript to vascular smooth muscle cells in small unremodeled vessels. Positive cells are purple (arrow). Larger remodeling vessels were negative (arrowhead). B, Negative controls included RNAse digested tissue or sections hybridized with the renin sense probe as shown here. C, Immunostaining for ACE in first-trimester decidua localized expression to spiral artery endothelial cells. Positive cells are reddish brown (arrow). Positive staining was also detected in surrounding stromal cells (arrowhead). D, IgM-negative controls were negative. E, Immunostaining for AT1 in first-trimester decidua localized expression to perivascular stroma. Positive cells are purple (arrows). As expected, some spiral artery smooth muscle cells were also faintly positive (data not shown). F, Negative controls using purified rabbit immunoglobulins at the same concentration as the AT1 antibody were negative. Sections were counterstained with eosin (A, B) or hematoxylin (C through F). Scale bar=150 µm.

ACE Expression Localized to Stroma and Endothelial Cells
Immunostaining for ACE in fetal heart demonstrated the expected pattern in the atrial myocardium.¹² In first-trimester decidua, ACE expression localized to spiral artery endothelial cells (Figure 2C). Positive cells were confirmed to be endothelial cells by the presence of von Willebrand factor staining in serial sections. Some perivascular decidual stromal cells also stained for ACE (Figure 2C). IgM-negative controls showed no staining of spiral artery endothelium or decidual stroma (Figure 2D). The ACE antibody and IgM controls both stained decidual epithelial glands, suggesting that this signal was an artifact (data not shown).

AT₁ Expression Localized to Stroma and Vascular Smooth Muscle Cells
Endothelial cells in fetal placenta and kidney immunostained for AT₁ as expected.¹³ In first-trimester decidua, AT₁ expression localized to perivascular stromal cells (Figure 2E). Spiral artery smooth muscle cells also demonstrated faint signal, but staining was only marginally above background. Negative controls using purified rabbit immunoglobulins at the same concentration as the AT₁ antibody were negative (Figure 2F).

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
Spiral Artery RAS Expression
In this study, we show for the first time in humans that all the components of the vascular RAS are expressed in and around remodeling spiral arteries. Decidual spiral arteries are some of the most vasoactive vessels in the body.¹ Therefore, it is not surprising that a local RAS is present and may play a role in pregnancy-induced remodeling.

Johnson et al¹⁸ showed that renin is present in spiral artery smooth muscle cells and that it may mediate uteroplacental blood flow. However, the source of renin in the spiral artery wall was in question because renin may be taken up from the circulation by the vessel wall.¹⁹ We chose to localize renin expression in first-trimester decidua by in situ hybridization because of the recent controversy over immunostaining for human renin. Antibodies raised against human renin may cross-react with reninlike proteases in human placenta and fetal membranes.²⁰ Our data support the hypothesis that renin is expressed locally.²¹

Spiral artery endothelium expresses ACE similarly to other vessels.⁵ We also observed staining for ACE in perivascular stromal cells. This observation is consistent with cell culture experiments suggesting that ACE is probably expressed by human decidual stromal cells.²²

Finally, we demonstrated staining for AT₁ receptors in spiral artery smooth muscle cells and perivascular stroma. In the human placenta the receptor is of the AT₁ subtype,¹³ and others have shown that AT₁ is expressed by uterine vascular smooth muscle cells in sheep.²³ Although AT₁ is usually identified by radioligand binding studies,²⁴ we made use of a polyclonal antibody raised against rat AT₁. Rat AT₁ and human AT₁ share 94.7% identity, and this antibody stained renal and placental positive controls as expected. We concluded therefore that this antibody labeled human AT₁ in decidua.

Role of Spiral Artery RAS
We suspect that local AGT expression is necessary for normal pregnancy-induced dilation of the spiral arteries. Experiments in primates have shown that the infusion of low levels of angiotensin II causes increased prostaglandin synthesis, spiral artery dilation, and increased uteroplacental blood flow.^{25 26} However, high doses of angiotensin II decrease uteroplacental blood flow because of a relative increase in uteroplacental vascular resistance.²⁶ ACE inhibitors also lead to reduced uteroplacental blood flow.²⁷ These observations suggest that a low level expression of the AGT gene in remodeling spiral arteries may be involved in the normal dilation and attenuation of these vessels. However, abnormally elevated local expression may affect uteroplacental vascular resistance. Moreover, because angiotensin II is a potent mitogen and angiogenic agent, abnormally elevated local angiotensin II levels may cause medial hyperplasia²⁸ and/or angiogenesis²⁹ in remodeling spiral arteries.

In addition, the spiral artery RAS may be involved in decidualization. Both in vivo and in vitro studies performed in rats suggest that angiotensin II is required for decidualization.³⁰ The inhibition of ACE prevented decidualization, whereas infusion of angiotensin II stimulated decidualization. In humans, decidualization begins around the spiral arteries and then spreads throughout the endometrium.³¹ In fact, there is evidence that the early stages of spiral artery remodeling may be a form of decidualization.³

Spiral Artery RAS and Preeclampsia
Recent transgenic mouse studies suggest that increased expression of maternal AGT plays a role in the pathogenesis of preeclampsia.³² Takimoto et al³² showed that pregnant mice expressing the human AGT (hAGT) gene develop a preeclampsia-like syndrome when the fetus expresses the human renin (hREN) gene. Pregnant females displayed a transient elevation of blood pressure late in pregnancy, which returned to normal after delivery of the pups. Histopathologic analysis also revealed uniform enlargement of the glomeruli associated with an increase in urinary protein. These transgenic mice overexpress both of these genes, but the location of hAGT and hREN expression appears to be important. Indeed, the syndrome did not develop when the mother expressed human renin and the fetus expressed hAGT. Although further experimentation is required (eg, to confirm that fetal hAGT is available for maternal hREN cleavage and that simply infusing human renin into an hAGT transgenic mouse does not lead to preeclampsia), this model suggests that perhaps the systemic RAS is not as important as a local uteroplacental RAS in the pathogenesis of preeclampsia.

We have suggested that molecular variants of the AGT gene may have a role in preeclampsia.³³ In our study population, 20% of white women homozygous for the AGT T235 variant (Met235Thr) developed preeclampsia compared with <1% of white women homozygous for the M235 allele. We attribute the association between T235 and preeclampsia to a mutation in the AGT promoter A(-6), which is in very tight linkage disequilibrium with T235.³⁴ Tests of promoter function and studies of binding between AGT oligonucleotides and nuclear proteins strongly suggest that the substitution at nucleotide -6 affects specific interactions between at least 1 trans-acting nuclear factor and the AGT promoter, thereby influencing the basal rate of transcription of the gene.

AGT T235 expression is elevated in decidual spiral arteries.⁴ Because the renin-AGT reaction is the rate-limiting step in the generation of angiotensin II, and because the plasma concentration of AGT is near the K_m value, any abnormal elevation in local AGT expression would lead to abnormally high local angiotensin II levels and decreased uteroplacental blood flow.³⁵ Consequently, women with the T235 variant allele may develop more spiral artery medial hyperplasia and/or angiogenesis during pregnancy-induced remodeling. In fact, we have recently observed a greater frequency of abnormal physiological change in women homozygous for the T235 variant compared with women homozygous for the M235 allele.³⁶ We hypothesize that relatively abnormal physiological change in TT women leads to an imbalance between maternal blood flow and placental demand, resulting in the cascade of events culminating in preeclampsia.

Indeed, improved spiral artery remodeling in women homozygous for M235 may explain the expansion of this allele in northern European whites.³⁷ Protection from preeclampsia is clearly an advantage for the mother and the fetus. We suggest that a selective pressure for fixing M235 in this population may be improved survival of the mother and child.

	Acknowledgments

 
This work was supported by a grant from The Willard L. Eccles Charitable Trust, the March of Dimes (6-FY95-0193), the National Center for Research Resources (M01-RR00064), and the National Institutes of Health (1R01-HD 32170-01). Kenneth Ward is an Investigator in the Eccles Program in Human Molecular Biology and Genetics.

	Footnotes

 
Reprint requests to Kenneth Ward, MD, Eccles Institute of Human Genetics, Room 2420, 2030 East 10 North, Salt Lake City, UT 84112.

Received April 13, 1998; first decision May 19, 1998; accepted June 19, 1998.

	References

Top Abstract Introduction Methods Results Discussion References

 
1. Brosens I, Robertson W, Dixon H. The physiological response of the vessels of the placental bed to normal pregnancy. J Path Bact. 1967;93:569–579.

2. Brosens I, Robertson W, Dixon H. The role of the spiral arteries in the pathogenesis of preeclampsia. Obstet Gynecol. 1972;1:177–191.

3. Craven CM, Morgan T, Ward K. Decidual spiral artery remodeling begins before cellular interaction with trophoblasts. Placenta. 1998;19:241–252.[Medline] [Order article via Infotrieve]

4. Morgan T, Craven C, Nelson L, Lalouel J-M, Ward K. Angiotensinogen T235 expression is elevated in decidual spiral arteries. J Clin Invest. 1997;100:1406–1415.[Medline] [Order article via Infotrieve]

5. Caldwell P, Seegal B, Hsu K, Das M, Soffer R. Angiotensin converting enzyme: vascular endothelial localization. Science. 1976;191:1050–1051.[Abstract/Free Full Text]

6. Gunther S, Gimbrone M, Alexander R. Identification and characterization of the high affinity vascular angiotensin II receptor in rat mesenteric artery. Circ Res. 1980;47:278–286.[Free Full Text]

7. Samani N, Morgan K, Brammar W, Swales J. Detection of renin messenger RNA in rat tissues: increased sensitivity using an RNAse protection technique. J Hypertens. 1987;5:S19–S21.

8. Naftilan A, Zuo W, Ingelfinger J, Ryan T, Pratt R, Dzau V. Localization and differential regulation of angiotensinogen mRNA expression in the vessel wall. J Clin Invest. 1991;87:1300–1311.

9. Paul M, Wagner J, Dzau V. Gene expression of the renin-angiotensin system in human tissues. J Clin Invest. 1993;91:2058–2064.

10. Gibbons G, Dzau V. The emerging concept of vascular remodeling. N Engl J Med. 1994;330:1431–1438.[Free Full Text]

11. Gomez R, Lynch K, Sturgill B, Elwood J, Chevalier R, Carey R, Peach M. Distribution of renin mRNA and its protein in the developing kidney. Am J Physiol. 1989;257:F850–F858.[Abstract/Free Full Text]

12. Endo-Mochizuki Y, Mochizuki N, Sawa H, Takada A, Okamoto H, Kawaguchi H, Nagashima K, Kitabatake A. Expression of renin and angiotensin-converting enzyme in human hearts. Heart Vessels. 1995;10:285–293.[Medline] [Order article via Infotrieve]

13. Kalenga M, Gasparo MD, Hertogh RD, Whitebread S, Vankrieken L, Thomas K. Angiotensin II receptors in the human placenta are type AT1. Nutr Dev. 1991;31:257–267.

14. Chomczynski P. A reagent for the single-step simultaneous isolation of RNA, DNA and proteins from cell and tissue samples. Biotechnology. 1993;15:532–537.

15. Morris B. New possibilities for intracellular renin and inactive renin now that the structure of the human renin gene has been elucidated. Clin Sci. 1986;71:345–355.[Medline] [Order article via Infotrieve]

16. Soubrier F, Alhenc-Gelas F, Hubert C, Allegrini J, John M, Tregear G, Corbol P. Two putative active centers in human angiotensin I-converting enzyme revealed by molecular cloning. Proc Natl Acad Sci U S A. 1988;85:9386–9390.[Abstract/Free Full Text]

17. Mauzy C, Hwang O, Egloff A, Wu L-H, Chung F-Z. Cloning, expression, and characterization of a gene encoding the human angiotensin II type 1A receptor. Biochem Biophys Res Commun. 1992;186:277–284.[Medline] [Order article via Infotrieve]

18. Johnson J. The site of renin in the human uterus. Histopathology. 1984;8:273–278.[Medline] [Order article via Infotrieve]

19. Loudon M, Bing R, Thurston H, Swales J. Arterial wall uptake of renal renin and blood pressure control. Hypertension. 1983;5:629–634.[Abstract/Free Full Text]

20. Hanssens M, Vercruysse L, Verbist L, Pijnenborg R, Keirse M, Assche FAV. Renin-like immunoreactivity in human placenta and fetal membranes. Histochem Cell Biol. 1995;104:435–442.[Medline] [Order article via Infotrieve]

21. Shaw K, Do Y, Kjos S, Anderson P, Shinagawa T, Dubeau L, Hsueh W. Human decidua is a major source of renin. J Clin Invest. 1989;83:2085–2092.

22. Alhenc-Gelas F. Angiotensin I converting enzyme in foetal membranes and chorionic cells in culture. J Hypertens. 1984;2:247–249.

23. Rosenfeld C, Cox B, Magness R, Shaul P. Ontogeny of angiotensin II vascular smooth muscle receptors in ovine fetal aorta and placental and uterine arteries. Am J Obstet Gynecol. 1993;168:1562–1569.[Medline] [Order article via Infotrieve]

24. Healey D, Maciejewski A, Printer M. Autoradiographic localization of (125I) angiotensin II binding sites in the rat adrenal gland. Endocrinology. 1985;116:1221–1223.[Abstract/Free Full Text]

25. Speroff L, Haning R, Levin R. The effect of angiotensin II and indomethacin on uterine artery blood flow in pregnant monkeys. Obstet Gynecol. 1977;50:611–614.[Medline] [Order article via Infotrieve]

26. Naden R, Rosenfeld C. Effect of angiotensin II on uterine and systemic vasculature in pregnant sheep. J Clin Invest. 1981;68:468–474.

27. Ferris T, Weir E. Effect of captopril on uterine blood flow and prostaglandin E synthesis in the pregnant rabbit. J Clin Invest. 1983;71:809–815.

28. Dzau V, Gibbons G, Pratt R. Molecular mechanisms of vascular renin-angiotensin system in myointimal hyperplasia. Hypertension. 1991;18(suppl II):II-100–II-105.

29. Fernandez L, Twickler J, Mead A. Neovascularization produced by angiotensin II. J Lab Clin Med. 1985;105:141–145.[Medline] [Order article via Infotrieve]

30. Squires P, Kennedy T. Evidence for a role for a uterine renin-angiotensin system in decidualization in rats. J Reprod Fertil. 1992;95:791–802.[Abstract/Free Full Text]

31. Bernirschke K, Kaufmann P. Structural aspects of decidualization. In: Bernirschke K, ed. Pathology of the Human Placenta. New York, NY: Springer-Verlag; 1990:257.

32. Takimoto E, Ishida J, Sugiyama F, Horiguchi H, Murakami K, Fukamizu A. Hypertension induced in pregnant mice by placental renin and maternal angiotensinogen. Science. 1996;274:995–997.[Abstract/Free Full Text]

33. Ward K, Hata A, Jeunemaitre X, Helin C, Nelson L, Namikawa C, Farrington P, Ogasawara M, Suzumori K, Tomoda S, Berrebi S, Sasaki M, Corvol P, Lifton R, Lalouel J-M. A molecular variant of angiotensinogen associated with preeclampsia. Nat Genet. 1993;4:59–61.[Medline] [Order article via Infotrieve]

34. Inoue I, Nakajima T, Williams C, Quackenbush J, Puryear R, Powers M, Cheng T, Ludwig E, Sharma A, Hata A, Jeunemaitre X, Lalouel J-M. A nucleotide substitution in the promoter of human angiotensinogen is associated with essential hypertension and affects basal transcription. J Clin Invest. 1997;99:1786–1797.[Medline] [Order article via Infotrieve]

35. Poulsen K. Kinetics of the renin system: the basis for determination of the different components of the system. Scand J Clin Lab Invest. 1973;31:1–86.[Medline] [Order article via Infotrieve]

36. Morgan T, Craven C, Lalouel J-M, Ward K. Angiotensinogen T235 is associated with abnormal physiologic change of the uterine spiral arteries in first trimester decidua. Am J Obstet Gynecol. 1998. In press.

37. Jeunemaitre X, Soubrier F, Kotelevtsev Y, Lifton R, Williams C, Charru A, Hunt S, Hopkins P, Williams R, Lalouel J-M, Corvol P. Molecular basis of human hypertension: role of angiotensinogen. Cell. 1992;71:169–180.[Medline] [Order article via Infotrieve]

This article has been cited by other articles:

				L. Anton, D. C. Merrill, L. A.A. Neves, K. Stovall, P. E. Gallagher, D. I. Diz, C. Moorefield, C. Gruver, C. M. Ferrario, and K. B. Brosnihan Activation of Local Chorionic Villi Angiotensin II Levels But Not Angiotensin (1-7) in Preeclampsia Hypertension, April 1, 2008; 51(4): 1066 - 1072. [Abstract] [Full Text] [PDF]

				M. Paul, A. Poyan Mehr, and R. Kreutz Physiology of local Renin-Angiotensin systems. Physiol Rev, July 1, 2006; 86(3): 747 - 803. [Abstract] [Full Text] [PDF]

				H. A. Kadi, H. Nasrat, and F. B. Pipkin A prospective, longitudinal study of the renin-angiotensin system, prostacyclin and thromboxane in the first trimester of normal human pregnancy: association with birthweight Hum. Reprod., November 1, 2005; 20(11): 3157 - 3162. [Abstract] [Full Text] [PDF]

				E. Takimoto-Ohnishi, T. Saito, J. Ishida, J. Ohnishi, F. Sugiyama, K.-I. Yagami, and A. Fukamizu Differential Roles of Renin and Angiotensinogen in the Feto-Maternal Interface in the Development of Complications of Pregnancy Mol. Endocrinol., May 1, 2005; 19(5): 1361 - 1372. [Abstract] [Full Text] [PDF]

				D. M. Shah Role of the renin-angiotensin system in the pathogenesis of preeclampsia Am J Physiol Renal Physiol, April 1, 2005; 288(4): F614 - F625. [Abstract] [Full Text] [PDF]

				S. Levesque, J.-M. Moutquin, C. Lindsay, M.-C. Roy, and F. Rousseau Implication of an AGT Haplotype in a Multigene Association Study With Pregnancy Hypertension Hypertension, January 1, 2004; 43(1): 71 - 78. [Abstract] [Full Text] [PDF]

				G. Mello, E. Parretti, F. Gensini, E. Sticchi, F. Mecacci, G. Scarselli, M. Genuardi, R. Abbate, and C. Fatini Maternal-Fetal Flow, Negative Events, and Preeclampsia: Role of ACE I/D Polymorphism Hypertension, April 1, 2003; 41(4): 932 - 937. [Abstract] [Full Text] [PDF]

				Y. Yamamoto, T. Maruyama, N. Sakai, R. Sakurai, A. Shimizu, T. Hamatani, H. Masuda, H. Uchida, H. Sabe, and Y. Yoshimura Expression and subcellular distribution of the active form of c-Src tyrosine kinase in differentiating human endometrial stromal cells Mol. Hum. Reprod., December 1, 2002; 8(12): 1117 - 1124. [Abstract] [Full Text] [PDF]

				M. Ito, A. Itakura, Y. Ohno, M. Nomura, T. Senga, T. Nagasaka, and S. Mizutani Possible Activation of the Renin-Angiotensin System in the Feto-Placental Unit in Preeclampsia J. Clin. Endocrinol. Metab., April 1, 2002; 87(4): 1871 - 1878. [Abstract] [Full Text] [PDF]

				K. F. Hilgers, C. Delles, R. Veelken, and R. E. Schmieder Angiotensinogen Gene Core Promoter Variants and Non-Modulating Hypertension Hypertension, December 1, 2001; 38(6): 1250 - 1254. [Abstract] [Full Text] [PDF]

				F. Clayton, D. P. Kotler, S. K. Kuwada, T. Morgan, C. Stepan, J. Kuang, J. Le, and J. Fantini Gp120-Induced Bob/GPR15 Activation : A Possible Cause of Human Immunodeficiency Virus Enteropathy Am. J. Pathol., November 1, 2001; 159(5): 1933 - 1939. [Abstract] [Full Text] [PDF]

				R. N. Re On Not Being the Last to Give Up the Old or the First to Adopt the New Hypertension, October 1, 2001; 38(4): 759 - 760. [Full Text] [PDF]

				M. Christiansen, I. Jaliashvili, M. T. Overgaard, C. Ensinger, P. Obrist, and C. Oxvig Quantification and Characterization of Pregnancy-associated Complexes of Angiotensinogen and the Proform of Eosinophil Major Basic Protein in Serum and Amniotic Fluid Clin. Chem., August 1, 2000; 46(8): 1099 - 1105. [Abstract] [Full Text] [PDF]

				C. Li, R. Ansari, Z. Yu, and D. Shah Definitive Molecular Evidence of Renin-Angiotensin System in Human Uterine Decidual Cells Hypertension, August 1, 2000; 36(2): 159 - 164. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Morgan, T. Articles by Ward, K. Search for Related Content PubMed PubMed Citation Articles by Morgan, T. Articles by Ward, K.