Calcium magnesium ATPase activity in homogenates of the placenta and myometrium of pregnant women and parturients

The authors determined total and specific activity (Ca2+, Mg2+) ATPase in homogenates of uterus muscle, placenta, amnion and chorion. The material was also studied for the levels of ATP, ADP and AMP in order to evaluate the energetic potential. The research was carried out in two groups: among 23 pregnant women who underwent Cesarean section not accompanied by labour pains and among 30 women in labour in whom labour pains lasted up to six hours and then labour was completed by Cesarean section. It was found that in advanced pregnancy the highest enzyme activity is in chorion homogenates. Labour pains result in decrease in enzyme activity in the material studied; the highest significant decrease observed in chorion. It was also found that labour pains do not result in greater changes in energetic potential of tissues except for chorion and amnion. The results obtained point to particular participation of chorion in the process of active transportation of calcium ions in pregnancy and delivery. The consequence of change in enzyme activity will be changes in the level of Ca2+ ions, which will result in the activation or inhibition of various metabolic tracts on cellular level, including hormonal changes.     

Altered mRNA expression of ecNOS and iNOS in myometrium and placenta from women with preeclampsia

Objective: Preeclampsia is a syndrome involving dysfunction of vascular endothelium and imbalance between endothelium derived constricting and relaxing factors. Recent evidence suggests that endothelium-derived nitric oxide (NO) plays a role in the regulation of vascular resistance during normal pregnancy and preeclampsia. NO is a potent vasodilator and is generated by the catalytic action of nitric oxide synthases ecNOS and iNOS in myometrium and placenta. Methods: In this study mRNA expressions of ecNOS and iNOS were compared in myometrium and placenta. Biopsies were collected from women with preeclampsia (n=8) and normal pregnancies (n=12). ecNOS and iNOS mRNA levels were determined using RT-PCR and expressed as arbitrary units after correction for control GAPDH gene mRNA levels. Results: The mRNA expression of ecNOS was significantly higher in both myometrium (p<0.05) and placenta (p<0.05) from women with preeclampsia compared to that in normal pregnancies, while the iNOS mRNA level was not altered in myometrium and lower in placenta (p<0.05) from women with preeclampsia. Conclusions: The higher ecNOS mRNA expression might be a compensatory response to an impaired vasodilatation in the uteroplacental circulation during preeclampsia. Whether the similar and reduced levels of iNOS mRNA expression in myometrium and placenta, respectively, in women with preeclampsia is of importance remains to be further evaluated. Received: 30 October 2000 / Accepted: 30 October 2000     

Energy metabolism of the myometrium in pregnancy and labor

The strips of uterine muscle were taken during the caesarean section and the levels of energetic substrates (glycogen and FFA), glycolysis products (pyruvate and lactate), highenergetic phosphates were estimated and the activity of selected carbohydrate metabolism enzymes was tested--in the homogenates in relation to the type of uterine contractility. Further the protein metabolism enzymes were estimated also (AspAT, ALAT, GlDH); including CPK. It was demonstrated that the energetic metabolism of the uterine muscle is different in pregnancy and in labour and depends on the type of uterine contractility.     

P-selectin in placenta and gestational myometrium: its measurements and hypothetical role in hemostasis of placental bed after labor

AIM: P-selectin is a member of selectin family (E, L- and P-selectins) which plays a crucial role in reproduction and hemostasis as well as in pathogenesis of preeclampsia. There are no regular studies on P-selectin in placenta and it is not clear whether it is present in gestational myometrium. In the present study, we have asked whether P-selectin is present in placenta and myometrium and in what concentration. MATERIAL AND METHODS: The study group consisted of 33 healthy pregnant women at term and/or at the beginning of labor who delivered by cesarean section because of fetal distress or elective reasons. Strips of placenta and myometrium as well as venous blood were obtained during the operation. P-selectin was measured in tissue extracts and plasma with the use of immunoenzymatic assays (ELISA). RESULTS: The median of the level of P-selectin in placenta was 31.65 ng/mg P (total protein), quartiles (Q1-Q3): 24.54-43.35 ng/mg P, and in myometrium 25.54 ng/mg P, quartiles (Q1-Q3): 21.83-35.65 ng/mg P, whereas the median and quartiles (Q1-Q3) of soluble P-selectin in the mother's plasma was 1.14: 0.76-1.63 ng/mg P. The plasma/tissue ratio for placenta was 1:30, and for myometrium -1:25. CONCLUSIONS: P-selectin is present in placenta and gestational myometrium; its concentration is relatively high - respectively 30- and 25-times higher than in plasma. On the basis of our studies, we hypothesize about the role of placental and myometrial P-selectin in hemostasis of placental bed after labor.     

Changes in expression of the cyclooxygenase gene in human fetal membranes and placenta with labor.

OBJECTIVE: Our objective was to examine the expression of the gene coding for cyclooxygenase, the central enzyme in prostaglandin synthesis, in human placenta and fetal membranes during pregnancy and before and after labor at term. STUDY DESIGN: Expression of the gene for cyclooxygenase was examined with Northern hybridization to ribonucleic acid from human placenta throughout pregnancy and human amnion and chorion decidua in the late third trimester. RESULTS: Expression was undetectable in trophoblast during the first and second trimesters. Expression in amnion and trophoblast increased 3.5- and 2.5-fold, respectively, in association with labor. CONCLUSIONS: Our results suggest that the increase in prostaglandin synthesis within the uterus that is seen with the onset of labor is associated with an increase in the expression of the gene cyclooxygenase.     

分娩发动前后胎盘中白细胞抗原G1 mRNA和NK细胞的变化

目的:检测胎盘及蜕膜组织中白细胞抗原G1(HLA-G1)mRNA和NK细胞在足月妊娠分娩发动前后的变化,探讨其在分娩发动中的作用。方法:通过RT-PCR法检测足月妊娠晚期未临产组(剖宫产组)和临产组胎盘组织中HLA-G1 mRNA的表达,并用免疫组织化学方法测定蜕膜中NK细胞的数量。结果:与未临产组相比临产组胎盘组织中HLA-G1 mRNA表达明显下降,差异有统计学意义(P<0.05);临产组蜕膜中NK细胞数量明显多于未临产组(P<0.05)。结论:分娩发动时胎盘组织表达HLA-G1mRNA下降,蜕膜组织中NK细胞数量明显增多,推测HLA-G1表达下降激活NK细胞可能参与了分娩发动。     

人子宫肌层诱导型环加氧酶剪接变异体cDNA片段的克隆和序列测定

目的 寻找人子宫肌层诱导型环加氧酶(cyclooxygenase-2,COX—2)选择性剪接变异体。方法 运用自行设计的COX—2 mMA引物,采用逆转录聚合酶链反应(RT—PCR)技术,分离临产与未临产产妇子宫肌层COX—2 mMA,再对电泳所获条带进行亚克隆、测序。结果 未临产产妇子宫肌层未检测到COX—2 mRNA,临产产妇子宫肌层不仅检测到COX—2 mRNA,而且分离出一新条带,经亚克隆及测序,证实该条带系人子宫肌层COX—2蛋白DNA的第7、8外显子间的内含子序列被保留所致。结论 临产产妇子宫肌层COX—2 mRNA存在选择性剪接变异体。该变异体的发现,为分娩机制的阐明及前列腺素代谢异常相关性疾病的防治提供了新的研究方向。     

Tissue-specific ontogenic expression of prostaglandin H synthase 2 in the ovine myometrium, endometrium, and placenta during late gestation and at spontaneous term labor

OBJECTIVE: The purposes of this study were to determine (1) whether uterine tissues as well as the fetal placenta are involved in the development of prostaglandin-synthesizing capacity associated with impending labor in pregnant sheep and (2) whether the key enzyme of prostaglandin synthesis, prostaglandin H synthase 2, is differentially expressed in the different intrauterine tissues during late gestation and in association with labor. STUDY DESIGN: Myometrium, endometrium, and fetal placenta were removed from ewes at 95 days' gestation, (n = 3), 101 to 110 days' gestation (n = 3), 111 to 120 days' gestation (n = 3), 121 to 130 days' gestation (n = 3), 131 to 140 days' gestation (n = 3), and 141 to 145 days' gestation (n = 4) and from ewes in spontaneous term labor at 143 to 147 days' gestation (n = 4). Expressions of prostaglandin H synthase 2 messenger ribonucleic acid and protein were determined by Northern blot and Western blot analyses. Prostaglandin H synthase 2 was localized in the fetal placenta by immunohistochemical means. RESULTS: Levels of both prostaglandin H synthase 2 messenger ribonucleic acid and protein increased gradually from 115 days' gestation in the fetal placenta and from 131 days' gestation in the endometrium. A further and more significant increase in prostaglandin H synthase 2 concentration occurred in the placenta and endometrium during spontaneous term labor. In contrast, myometrial concentrations of prostaglandin H synthase 2 messenger ribonucleic acid and protein remained at steady basal levels during the course of pregnancy and increased only during labor. Prostaglandin H synthase 2 was localized in the trophoblast cells of the fetal placenta. CONCLUSIONS: Tissue-specific ontogenic expression of prostaglandin H synthase 2 was observed in myometrium, endometrium, and placenta during late ovine gestation and spontaneous term labor. Fetal placenta and endometrium showed increased expression of prostaglandin H synthase 2 messenger ribonucleic acid and protein during late ovine gestation, whereas myometrial prostaglandin H synthase 2 concentration remained low throughout late gestation. Prostaglandin H synthase 2 concentrations in the myometrium, endometrium, and placenta are all upwardly regulated during labor.