| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Articles |
a Department of Obstetrics and Gynecology/Perinatal Research Laboratories, and
b Department of Animal Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53715
c The Monroe Clinic, Monroe, Wisconsin 53566
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
In both pregnant and nonpregnant sheep, PGI2 is the primary prostaglandin produced by uterine artery endothelial cells, with only small quantities derived from the vascular smooth muscle (VSM) [9–13]. Previously we have shown that the de novo production of PGI2 in vitro by uterine artery endothelium from pregnant sheep is greater than that observed for nonpregnant ewes [10–12], although the magnitude of the pregnancy-related increase was greater (5- to 6-fold) when compared to that in the uterine arteries obtained from ovariectomized sheep [10] rather than ovary-intact sheep [11, 14]. Moreover, production of PGI2 by uterine arteries placed in tissue culture was less in ovariectomized as compared to intact sheep [14] and in uterine arteries from postmenopausal versus premenopausal women [15]. Therefore, changes in PGI2 production during pregnancy and the ovarian cycle may be regulated, in part, via increases in the activity and/or the expression of COX-1 at the level of protein and mRNA. This theory is supported by the proportionally greater PGI2 production by uterine arteries from pregnant versus nonpregnant ewes during incubation in the presence of excess arachidonic acid, the substrate for COX [11]. Previously we have shown, in freshly isolated uterine artery endothelial cells from pregnant and nonpregnant sheep, that COX-1 expression is elevated at the level of both protein and mRNA in pregnancy [16]. However, since pregnancy is a state of both high estrogen and progesterone, it is possible that either or both of these steroid hormones are responsible for this response [2, 17–19]. During the follicular phase of the ovarian cycle there is also an increase in uterine blood flow, whereas decreases are observed during the luteal phase [17, 20]. In contrast to the pregnant state, however, the follicular phase is characterized as an estrogen-dominated state, and the luteal phase is a progesterone-dominated state [18, 21].
Cyclooxygenase exists in two isoforms, COX-1 and COX-2 [22]. COX-1 is "constitutively" expressed in many tissues [23] including uterine tissues (endometrium and myometrium; [24–27]), as well as in pulmonary endothelial cells of ovine fetuses and lambs, in which it appears to regulate vascular homeostasis via production of prostanoids [28]. In contrast, COX-2 is induced by mitogens, lipopolysaccharides, and hCG in various tissues and is usually associated with inflammatory responses [13, 29–32]. COX-2 is also strongly induced in the uterus and placenta near term and during labor [24, 25, 33, 34]. It is not known, however, whether COX expression is also quantitatively regulated in uterine and systemic artery endothelium and VSM during the ovarian cycle and pregnancy.
In the current study we tested the hypothesis that during physiologic states that have high uterine blood flow, such as the follicular phase of the ovarian cycle [2, 17, 20] and pregnancy [2, 3, 17], there is an increase in uterine artery endothelial COX-1 and/or COX-2 expression. Our specific objectives were the following: 1) to localize the presence of COX-1 and COX-2 in the uterine arterial wall (endothelium versus VSM); 2) to determine whether there is a change in the uterine and/or systemic (omental) arterial expression of COX-1 and/or COX-2 in ovariectomized, follicular-phase, and luteal-phase sheep and to compare any such changes to those that occur in pregnant sheep; and 3) to determine whether changes in COX-1 protein expression could be due to underlying changes in COX-1 mRNA level. Clearly, knowledge of the magnitude and cellular location of any changes in uterine artery COX-1 and/or COX-2 expression in various physiological states would provide valuable insight into the possibility that endogenous ovarian/placental steroid-dependent mechanisms underlie control of uterine artery function and uterine blood flow.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Polypay and mixed western breed ewes, 50–60 kg (n = 21) were observed daily for signs of behavioral estrus in the presence of a vasectomized ram. Ewes exhibiting normal estrous cycles (16–18 days) were given 2 injections i.m., 5 mg each, of prostaglandin F2
(PGF2, Lutalyse; UpJohn, Kalamazoo, MI) 4 h apart in order to rapidly induce luteolysis, and the ewes were monitored for behavioral estrus beginning 40–44 h after the first PGF2 injection. Ewes exhibiting estrus (Day 0) were randomly assigned into two groups, follicular (Day -1 to 0, n = 11) or luteal (Day 10, n = 10). On Day 8 of the estrous cycle, the ewes assigned to the follicular group were given PGF2, as described above, and the ewes assigned to the luteal group were given saline (2 injections i.m., volume equivalent to that for PGF2, 4 h apart). With this synchronization protocol, ewes show estrus within 44–56 h after the first PGF2 injection. Follicular-phase ewes were killed 44 h after the first injection of PGF2, and the luteal-phase ewes were killed that same day at 44 h after the first saline injection.
Ovarian Structures
The diameters and presence of the ovarian corpora lutea and follicles were determined as previously described [13,14, 18, 35]. Small (1–3 mm), medium (4–5 mm), and large (
6 mm) follicles were measured and recorded. Luteal-phase ewes had significantly larger-diameter (9.6 ± 0.5 mm) and vascular corpora lutea as compared to follicular-phase ewes (P < 0.01), whose regressing corpora lutea (corpora albicans) were smaller (6.4 ± 0.4 mm), blanched, and avascular. Although the follicular-phase ewes had similar numbers of small and medium follicles, their large follicles had greater (P < 0.05) diameters (8.1 ± 0.7 mm) than those in the luteal-phase sheep (6.5 ± 0.3 mm). These data validate that the follicular-phase sheep were in a high-estrogen condition while the luteal-phase sheep were in a high-progesterone state, as previously reported [13, 14, 18, 35]. We also have previously reported the circulating estrogen and progesterone plasma levels using this animal model [18].
Ovariectomized Ewes
Polypay and mixed western breed ewes (50–60 kg; n = 10) that had previously had normal estrous cycles underwent uncomplicated ovariectomy (OVEX) using a midventral laparotomy under general anesthesia as previously described [14, 35]. Sheep underwent nonsurvival surgery on Days 10–11 postovariectomy, and the arteries were obtained as described below.
Tissue Collection
Polypay and mixed western breed sheep were bred at the University of Wisconsin-Madison Animal Sciences facility designated for these studies in order to obtain pregnant ewes (n = 12) at 120–130 days gestation. Procedure for animal handling and protocols for experimental procedures were approved by the University of Wisconsin-Madison Research Animal Care and Use Committees of both the Medical School and College of Agriculture and Life Sciences, and followed the 1993 "Report of the American Veterinary Medical Association Panel on Euthanasia." All ewes in this experiment were administered general anesthesia consisting of i.v. sodium pentobarbital (40–50 mg/kg) and then underwent nonsurvival surgery at the conclusion of the procedure. The uterine mesometrium, containing a portion of the main uterine artery, was removed rapidly (10–12 min) and placed in sterile PBS (pH 7.40) containing NaCl (137 mM), KCl (2.7 mM), Na2HPO4·7H2O (4.3 mM), and KH2PO4 (1.4 mM). Further dissection of arteries to remove fat and connective tissue was performed at 25°C in Petri dishes containing PBS. During dissection, the PBS was removed from the dish and replaced three times. The methods for the preparation of the intact or endothelium-denuded uterine or omental arterial segments, or direct mechanical isolation of endothelial protein for SDS-PAGE electrophoresis and Western immunoblotting, were reported by and validated previously in this laboratory [14, 16, 35–37]. Additional arterial segments were either subjected to collagenase dispersion or fixed for immunohistochemistry, as described below.
Western Immunoblot Analysis
The protocol for SDS-PAGE on 7.5% gels as well as subsequent Western immunoblot analysis, as described previously [14, 16, 35–37], was performed for 6 sheep in each of the OVEX, follicular-phase (FOL), and luteal-phase (LUT) groups and for 8 pregnant (PREG) sheep. COX-1-specific antiserum (Cayman Chemical Company, Ann Arbor, MI) was utilized at a dilution of 1:3000 overnight at room temperature, and a secondary antibody (sheep anti-mouse Fab2-horseradish peroxidase conjugate; Amersham; now Amersham Pharmacia Biotech, Piscataway, NJ) was used at 1:5000 dilution for 1 h. A positive control for COX-1, ram seminal vesicle (RSV), was included on each blot. Specific binding for COX-1 was detected using enhanced chemiluminescence reagent detection system, as described by Amersham, and exposed to Hyperfilm (5 min). Levels of COX-1 were quantified by scanning densitometry (Bio-Rad 670 scanning densitometer; Richmond, CA) and expressed relative to mean luteal absorbance.
COX-2-specific antiserum was rabbit polyclonal antibody (Cayman) at a dilution of 1:4000, and the secondary antibody was a goat anti-rabbit horseradish peroxidase conjugated (Amersham) at a dilution of 1:8000. The control for COX-2 was purified COX-2 from sheep cotyledons (Cayman). This COX-2 antibody has previously been shown to detect only COX-2, without any cross reaction with COX-1 [13, 14, 16].
Immunohistochemistry
Immunohistochemistry methods were similar to those we have previously reported [13, 16, 35–37] and were performed on representative uterine arteries from 4 to 5 ewes in each of the four treatment groups. Arteries were placed in 4% formaldehyde in sodium cacodylate buffer (0.1 M, pH 7.4) and fixed overnight. Tissues were sequentially dehydrated in graded ethanol solutions, embedded in paraffin, cut into sections (6 µm), and mounted on polylysine-coated glass slides. After deparaffinization and graded rehydration, sections were incubated in hyaluronidase for 30 min at 37°, followed by 3% H2O2 in 60% methanol for 20 min to quench endogenous peroxidase activity. COX-1 antibody (mouse monoclonal antibody; Cayman) was then applied (1:2000 dilution), and staining was detected using a biotinylated secondary antibody in combination with the avidin-biotin-peroxidase method (Elite ABC kit; Vector Laboratories, Burlingame, CA) with 3,3'-diaminobenzidine as chromagen. As controls, adjacent sections were alternatively treated with a control mouse IgG fraction (2.5 mg/ml; Vector), without primary antisera, or without second antibody. These control sections were routinely stained in parallel with each batch of uterine artery slides prepared from ovariectomized (n = 5) and nonpregnant, follicular-phase (n = 5) and luteal-phase (n = 4) animals, as well as from pregnant (n = 4) animals.
Isolation of Endothelial Cells and Cellular RNA
Uterine artery endothelial cells were isolated by collagenase dispersion as previously described [16, 37, 38] from 6 each of the ovariectomized, follicular-phase, and luteal-phase sheep and from 8 of the pregnant sheep. These freshly isolated endothelial cells were solubilized in RNAzol B (1 ml), and 150 µl chloroform was added to promote phase separation followed by centrifugation (12 000 x g, 20 min). The upper aqueous phase was then removed, extracted twice with phenol/chloroform/isoamyl alcohol using heavy grade phase-lock gel (Eppendorf 5-Prime, Boulder, CO), and finally mixed with 110% by volume of isopropanolol. RNA was precipitated by standing at -20°C for 1 h before recovery by centrifugation (12 000 x g, 30 min) and washing of the pellet in 75% ethanol. RNA was then solubilized in molecular biology grade water (5-Prime) and quantified by spectrophotometry before storage at -70°C.
COX-1 Reverse Transcription-Polymerase Chain Reaction (RT-PCR) Assay
COX-1 mRNA levels were quantified by coupled RT-PCR amplification in single-tube assays using avian myeloblastosis virus reverse transcriptase and Taq polymerase, essentially as described previously for ovine COX-1 [16]. Total cellular RNA (0.5 µg/tube) was incubated in a 50-µl final volume containing single-strength PCR buffer, 2 mM MgCl2, 10 nmol each dATP, dTTP, dCTP, dGTP, and 30 pmol each of forward and reverse temperature-matched primers, targeting amplification of 313 bases of the ovine COX-1 mRNA for 29 cycles. All data in each group were normalized to the mean glyceraldehyde-3-phosphate dehydrogenase content of each sample within each subgroup, determined by RT-PCR as previously described [38]. The standard curve for the COX-1 RT-PCR assay and the high degree of linearity were demonstrated in our previous publications using identical conditions [16].
Statistical Analysis
Data were analyzed by ANOVA or Student's t-test when applicable (SigmaStat; Jandel Scientific, San Rafael, CA). When ANOVA was significant, treatment means were compared using Bonferroni's multiple comparison test. A linear correlation was determined between COX-1 mRNA and protein using the least-squares method. Data are reported as means and SEM, and significance was accepted at P < 0.05.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
The COX-1 protein was detected at 70 kDa in agreement with the standard from RSV lysate. A standard curve was generated to ensure that COX-1 was detected in a linear fashion and consistent with our previous data [16]; to confirm that we were not detecting COX-2, we probed the blot specifically for that enzyme and obtained negative results (data not shown). The majority of COX-1 level in uterine arteries was consistently observed in the endothelium, as compared with the VSM (Fig. 1). Scanning densitometry showed 2.2-fold greater COX-1 levels in the intact versus denuded uterine arteries (VSM) and 6.1-fold greater levels in the endothelium compared to the VSM (P < 0.05).
|
While luteal-phase and ovariectomized sheep showed no difference in COX-1 expression in uterine artery endothelium, significantly more COX-1 was observed in follicular-phase ewes as compared to luteal-phase animals (Fig. 2, 1.5-fold the luteal level, P < 0.05). In addition, COX-1 expression in the uterine artery endothelium from pregnant ewes was substantially higher than in follicular-phase, luteal-phase (4.8-fold of luteal), or ovariectomized animals (P < 0.001). In contrast, the level of COX-1 detected in uterine artery VSM was very low, and there did not appear to be any major changes in COX-1 protein levels in VSM with treatment group (data not shown). Moreover, omental (systemic) artery endothelial COX-1 protein expression by Western immunoblot analysis was not significantly altered (P > 0.05) by ovariectomy, the phase of the ovarian cycle, or pregnancy (i.e., pregnant, follicular, and ovariectomized expressions were 0.547-, 1.27-, and 1.5-fold the luteal expression, respectively). These data suggest that the above changes in COX-1 expression between groups were specific to the uterine vasculature. Again as with the uterine artery VSM, COX-1 levels in omental artery VSM were comparatively extremely low and did not appear to change with treatment (data not shown).
|
Immunohistochemistry
Since the Western immunoblot data showed that the majority of the COX-1 protein was observed in the uterine artery endothelium, we confirmed this finding with immunohistochemistry (Fig. 3). The darkest staining for COX-1 was immunolocalized in the uterine artery endothelium, with some small amount of staining in the VSM. Furthermore, consistent with the Western immunoblot data shown in Figure 2, the arteries from the pregnant sheep and the follicular animals exhibited the most intense COX-1 staining with immunohistochemistry (Fig. 3). In addition, the uterine arteries from the luteal and ovariectomized animals stained the least, and there did not appear to be any substantial differences between these two groups. In some of the cross sections it appeared that the ovariectomized group may have had a little less staining than the luteal-phase group. We observed no immunostaining in the control segments in which either the primary antibody or the secondary antibody had been replaced with the nonimmune IgG serum. Because seminal vesicles are known to express large amounts of COX-1, but not COX-2 [16], we further validated this COX-1 antiserum by immunohistochemically staining rat seminal vesicles. This positive control intensely stained for COX-1 (data not shown).
|
COX-1 mRNA RT-PCR
RT-PCR was utilized to quantify COX-1 mRNA in collagenase-dispersed isolated uterine artery endothelial cells (Fig. 4) obtained from ovariectomized ewes (n = 6), as well as from sheep during the follicular and luteal phases of the ovarian cycle (n = 6 per group) and in pregnancy (n = 8). We observed relative levels of total COX-1 mRNA isolated from uterine artery endothelial cells similar to those from Western analysis except in the OVEX group; i.e., the rank order of COX-1 mRNA levels was PREG >>> FOL LUT > OVEX. The uterine artery endothelial COX-1 mRNA levels in follicular- and luteal-phase animals were both significantly greater than in OVEX controls; follicular levels tended to be greater than luteal-phase levels, but without achieving statistical significance. The level of COX-1 mRNA for pregnant ewes was substantially higher than that observed in all other groups. In the current study, however, we were further able to evaluate paired uterine artery endothelial COX-1 mRNA and protein samples from the same 6 sheep per nonpregnant group (OVEX, FOL, and LUT) as well as 8 pregnant sheep in order to study more directly the relationship between COX-1 mRNA and protein expression (Fig. 5). There was a significant linear correlation (r2 = 0.66) between COX-1 mRNA and protein across all groups, strongly suggesting that COX-1 expression is at least partly regulated at the mRNA level.
|
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
The production of the potent vasodilator PGI2 [1, 3] by the uterine vascular bed may be an important mediator of vascular tone during the follicular phase of the ovarian cycle [17]. In view of the direct relationship between elevations in the estrogen-to-progesterone ratio and uterine blood flow during the follicular phase of the ovarian cycle [17,18, 20, 21, 35], we were particularly interested in the effects that the phase of the ovarian cycle and ovariectomy had on endothelial and VSM expression of COX-1. We were unable to detect significant levels of COX-2 by Western blot analysis, confirming our recent findings that COX-2 protein expression in whole uterine arteries obtained from nonpregnant ewes in tissue culture was undetectable as compared to COX-1 levels. The observations that COX-1, but not COX-2, is expressed by ovine uterine artery endothelium and VSM have also been obtained immunohistochemically in luteal- and follicular-phase [13] as well as ovariectomized [26] sheep. We also demonstrated that COX-2 levels were specifically and dramatically elevated only in the presence of lipopolysaccharide [13, 14]. The current study, however, focused exclusively on the expression of COX in the basal state, and so focused on COX-1. These results were compared to those of pregnancy, a state of high estrogen and progesterone [2, 17–19] as well as elevated uterine artery endothelial PGI2 production [10–12].
Using immunohistochemistry we have extended our previous studies [16] to demonstrate that the expression of COX-1 is primarily seen in the endothelium—more so than in the VSM in all treatment groups. Consistent with this we have further demonstrated for the first time using Western immunoblot analysis that COX-1 expression was reduced considerably in denuded uterine arteries (VSM) as compared to intact vessels (Fig. 1) and that, while COX-1 is expressed in the VSM, its levels were 6.1-fold greater in endothelial-isolated protein preparations. Bovine aortic endothelial cells have also been shown to contain 20-fold higher concentrations of COX-1 than the VSM [42, 43]. These current observations are also consistent with previous studies [11, 12] from our laboratory showing that endothelium removal decreased PGI2 production by about 70%, suggesting that the uterine artery endothelium, to a greater extent than VSM, is the primary source of PGI2 production and COX-1 in both nonpregnant and pregnant sheep.
In the present study, we have clearly established the relative COX-1 protein levels by Western immunoblot analysis in uterine artery endothelium from ovariectomized, follicular-phase, luteal-phase, and pregnant ewes (Fig. 2). The relative order of protein expression for COX-1 in endothelium was PREG >>> FOL > LUT = OVEX. We thus report for the first time that COX-1 protein levels in follicular-phase animals are significantly elevated above those for luteal-phase animals; however, they are substantially increased over luteal- and follicular-phase levels by pregnancy. The observation FOL > LUT is consistent with previous reports by Chang et al. [44, 45], who showed that estradiol-17ß increased PGI2 synthesis and COX-specific activity in rat aortic smooth muscle cells, and also with findings of Jun et al. [46], who recently demonstrated that estradiol-17ß, acting through its receptor, increases the activity and mRNA and protein levels of COX-1 in cultured ovine fetal pulmonary artery endothelial cells. In contrast, when we compared ovine uterine artery PGI2 production and COX-1 protein levels after 24 h in tissue culture, we did not detect any difference when arteries were collected 2 h after vehicle versus estradiol-17ß treatment [14]. We also did not significantly alter uterine artery endothelial COX-1 expression with 10 days of continuous estradiol-17ß or progesterone treatment alone, whereas the combination of estradiol-17ß and progesterone did significantly increase COX-1 levels in uterine artery endothelium (unpublished results). In this regard, this latter comparison (estrogen plus progesterone) is consistent with our current and previous studies demonstrating that production of PGI2 and COX-1 expression by uterine artery endothelium was increased by pregnancy [10–12, 14], a state of elevated estrogen and progesterone levels [2, 17–19]. The increase in COX-1 protein levels observed during the follicular phase was not as great as that observed during pregnancy, suggesting that progesterone [2, 17, 18]—in combination with other components in pregnancy such as growth factors [2, 47–49], shear stress [50], or the length of time of exposure [2, 40, 41] to placental steroids (120–130 days)—caused the greater COX-1 elevation during gestation. Our previous studies also indicated that the production of PGI2 by uterine arteries from ovariectomized sheep was less than that from intact nonpregnant sheep [10–12, 14]. As evidenced by these findings, and in contrast to our hypothesis, the levels of COX-1 protein expression in endothelial-isolated protein were not significantly decreased in the OVEX group. It is possible that differences in the length of time postovariectomy in the two studies was responsible for the discrepant findings between uterine artery endothelial PGI2 production [10–12, 14] and COX-1 protein expression (Fig. 2).
We previously reported that omental artery endothelial PGI2 production [10–12] was increased in pregnant versus nonpregnant sheep, both in the absence and in the presence of saturating doses of arachidonate in vitro [11], suggesting that either the omental artery COX-1 expression or activity was increased with gestation. In the present study, we directly addressed the former and observed that the expression of COX-1 in omental (systemic) artery endothelial-isolated protein was not significantly altered by ovariectomy, the stage of the ovarian cycle, or pregnancy. These data also demonstrate that the increase in this systemic artery vasodilator during pregnancy cannot be explained by changes in the levels of the COX-1 protein; they rather suggest either an increased COX-1-specific activity or increased substrate release from membrane phospholipids. In recent studies we have observed that although the omental artery endothelial protein level of phospholipase A2 was unaltered [51] by pregnancy, the expression of PGI2 synthase protein was increased significantly [52].
The relative pattern of COX-1 mRNA across all groups was highly correlated with protein levels in the endothelium collected from the same animals. Unlike findings for the protein levels, however, while the rank order for COX-1 mRNA was PREG >>> FOL LUT, the level in OVEX ewes was lower than in both follicular- and luteal-phase sheep (P < 0.05). The dramatic increase in COX-1 mRNA during pregnancy confirms our previous observations [16]. The follicular-phase COX-1 mRNA was slightly, but not significantly, higher than the luteal-phase value, which otherwise related well to our observations of COX-1 protein levels by both Western analysis and immunohistochemistry. The significant difference in results for LUT versus OVEX at the level of mRNA alone, however, did not prevent a highly significant overall correlation (r2 = 0.66) of COX-1 mRNA versus protein levels in uterine artery endothelium from the same ewes across all treatment groups (Fig. 5). Thus we conclude that changes in COX-1 protein are largely driven at the level of changes in COX-1 mRNA. Other posttranscriptional or translational mechanisms may play a role in COX-1 expression, and this may explain the discrepancy between COX-1 protein levels and mRNA expression in the OVEX and LUT groups.
In conclusion, we have shown that in physiologic states of high uterine blood flow and estrogen such as the follicular phase of the ovarian cycle [17–20, 35], as well as pregnancy [2, 3], uterine artery endothelial COX-1 protein and mRNA are significantly elevated. Moreover, the increase in COX-1 expression in the follicular phase and pregnancy was specific to the uterine vascular bed and was not observed in the omental (systemic) arteries. This supports the hypothesis that uterine artery endothelial-derived COX-1 is, at least in part, regulated by the production of estrogen and/or progesterone. In contrast to our hypothesis regarding the ovariectomized state, which is estrogen and progesterone deficient and which exhibits reduced uterine artery PGI2 production [14, 39–41], there was not a significantly drop in uterine artery endothelial COX-1 protein levels; this suggests that other additional mechanisms remain to be identified. The increase in COX-1 protein levels observed during pregnancy was also greater than that observed during the follicular phase, demonstrating that several interacting factors in pregnancy (e.g., progesterone, growth factors, shear stress, etc.) contribute to the greater elevation of COX-1 expression.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
1 Supported by NIH HL49210, HL57653, HD33255, HL56702, WI Perinatal Foundation, and USDA 97352044912 and 960177. This study was presented at the 45th Annual Meeting of the Society for Gynecologic Investigation, Atlanta, GA, March 11–14, 1998. 
2 Correspondence: Ronald R. Magness, University of Wisconsin-Madison Medical School, Department of Obstetrics and Gynecology, Perinatal Research Laboratories, Meriter Hospital/Park-7E, 202 S. Park Street, Madison, WI 53715. FAX: 608 257 1304; rmagness{at}facstaff.wisc.edu
Accepted: September 30, 1999.
Received: April 22, 1999.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
-agonist. III. In vitro fetal-maternal placental prostaglandins. Am J Physiol 1991; 260:E8–E13.This article has been cited by other articles:
|
|
 |
|
  M. Li, L. Kuo, and J. N. Stallone Estrogen potentiates constrictor prostanoid function in female rat aorta by upregulation of cyclooxygenase-2 and thromboxane pathway expression Am J Physiol Heart Circ Physiol, June 1, 2008; 294(6): H2444 - H2455. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Chang and Lubo Zhang Review Article: Steroid Hormones and Uterine Vascular Adaptation to Pregnancy Reproductive Sciences, April 1, 2008; 15(4): 336 - 348. [Abstract] [PDF]
|
|
|
|
 |
|
 F. Meziani, A. Tesse, S. Welsch, H. Kremer, M. Barthelmebs, R. Andriantsitohaina, F. Schneider, and A. Gairard Expression and Biological Activity of Parathyroid Hormone-Related Peptide in Pregnant Rat Uterine Artery: Any Role for 8-Iso-Prostaglandin F2{alpha}? Endocrinology, February 1, 2008; 149(2): 626 - 633. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Tesse, F. Meziani, E. David, N. Carusio, H. Kremer, F. Schneider, and R. Andriantsitohaina Microparticles from preeclamptic women induce vascular hyporeactivity in vessels from pregnant mice through an overproduction of NO Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H520 - H525. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Hermenegildo, P.J. Oviedo, M.C. Garcia-Martinez, M.A. Garcia-Perez, J.J. Tarin, and A. Cano Progestogens stimulate prostacyclin production by human endothelial cells Hum. Reprod., June 1, 2005; 20(6): 1554 - 1561. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. McWhorter, S J. Carlan, T. D. O'Leary, K. Richichi, and W F. O'Brien Rofecoxib Versus Magnesium Sulfate to Arrest Preterm Labor: A Randomized Trial Obstet. Gynecol., May 1, 2004; 103(5): 923 - 930. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Ospina, S. P. Duckles, and D. N. Krause 17{beta}-Estradiol decreases vascular tone in cerebral arteries by shifting COX-dependent vasoconstriction to vasodilation Am J Physiol Heart Circ Physiol, June 5, 2003; 285(1): H241 - H250. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. M. Bird, L. Zhang, and R. R. Magness Possible mechanisms underlying pregnancy-induced changes in uterine artery endothelial function Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2003; 284(2): R245 - R258. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. Ospina, D. N. Krause, and S. P. Duckles 17{beta}-Estradiol Increases Rat Cerebrovascular Prostacyclin Synthesis by Elevating Cyclooxygenase-1 and Prostacyclin Synthase Stroke, February 1, 2002; 33(2): 600 - 605. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. L. Rupnow, T. M. Phernetton, M. L. Modrick, M. C. Wiltbank, I. M. Bird, and R. R. Magness Endothelial Vasodilator Production by Uterine and Systemic Arteries. VIII. Estrogen and Progesterone Effects on cPLA2, COX-1, and PGIS Protein Expression Biol Reprod, February 1, 2002; 66(2): 468 - 474. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. A. Buhimschi, G. Hall, L. P. Thompson, and C. P. Weiner Pregnancy and estradiol decrease GTPase activity in the guinea pig uterine artery Am J Physiol Heart Circ Physiol, November 1, 2001; 281(5): H2168 - H2175. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. T. Davidge Prostaglandin H Synthase and Vascular Function Circ. Res., October 12, 2001; 89(8): 650 - 660. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. R. Magness, J. A. Sullivan, Y. Li, T. M. Phernetton, and I. M. Bird Endothelial vasodilator production by uterine and systemic arteries. VI. Ovarian and pregnancy effects on eNOS and NOx Am J Physiol Heart Circ Physiol, April 1, 2001; 280(4): H1692 - H1698. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||
