Plasma adenosine levels and P-selectin expression on platelets in preeclampsia

OBJECTIVE: To measure the correlation of plasma adenosine levels with platelet activation in women with preeclampsia. METHODS: Plasma adenosine concentration and expression of P-selectin, a marker for platelet activation, were measured in 18 normal pregnant women and 18 preeclamptic women. The effect of 8-sulfophenyltheophylline, an adenosine receptor blocker, on expression of P-selectin on platelets also was measured. RESULTS: Plasma adenosine level averaged 0.77 +/- 0.11 microM (standard error of the mean [SEM]) in women with preeclampsia, significantly higher than the mean level of 0.47 +/- 0.08 microM in women with normal pregnancies (P <.05). Expression of P-selectin on platelets averaged 7.8 +/- 1.2% in women with preeclampsia, also significantly higher than the mean level of 4.7 +/- 0.7% in normal pregnancy (P <.05). Adenosine receptor blockade significantly increased expression of P-selectin on platelets in women with preeclampsia by 26% (P <.05), which was significantly higher than the 13% increase of activation in those with normal pregnancies (P <.05). CONCLUSION: Adenosine is an established platelet activation suppressor. Increased plasma levels of adenosine in preeclampsia might partially compensate and tend to prevent further excessive platelet activation in women with preeclampsia.     

The role of nitric oxide and blood platelets in pathogenesis of preeclampsia]

The aim of this study was to evaluate the concentration of nitric oxide and the platelet function in preeclamptic and normal pregnant women. The patients with preeclampsia had new hypertension (diastolic blood pressure consistently > or = 90 mmHg with previously lower readings), new proteinuria and generalized oedema that subsequently regressed after delivery. Blood was collected by routine forearm venipuncture before delivery. The following parameters were evaluated: nitric oxide, beta-TG and PF4. The nitric oxide plasma concentration in women with preeclampsia was significantly lower compared with normotensive pregnant women. beta-TG and PF4 concentrations were significantly increased in patients with preeclampsia. Whether these observations contribute to the vascular pathophysiologic features of preeclampsia remains to be proved.     

Endothelial dysfunction in preeclampsia. Increased homocysteine and decreased nitric oxide levels

Endothelial dysfunction underlies the pathogenesis of preeclampsia, but its mechanism has not yet been completely understood. Elevated oxygen free radicals may partially explain the endothelial cell damage. In this study, we have aimed to measure homocysteine (Hcy) and nitric oxide (NO) levels as endothelial dysfunction markers in preeclamptic women. Nineteen preeclamptic (33.9 +/- 1.4 weeks) and 15 gestational-age-matched normal pregnant women (35.5 +/- 0.7 weeks) were included in the study. Mean NO level was significantly lower (p < 0.001) and mean Hcy level was significantly higher (p < 0.001) in the preeclamptic group. Elevated Hcy and oxygen free radical levels could decrease NO levels due to the reaction with each other and reduced NO may increase blood pressure and ischemia in preeclamptic patients. We have concluded that increased Hcy and oxygen free radical levels, and decreased NO levels are closely associated with preeclampsia-related endothelial dysfunction.     

Plasma malondialdehyde, superoxide dismutase, sE-selectin, fibronectin, endothelin-1 and nitric oxide levels in women with preeclampsia

OBJECTIVE: The purpose of this study was to determine plasma malondialdehyde (MDA), superoxide dismutase (SOD), soluble E-selectin (sE-selectin), fibronectin, endothelin-1 (ET-1) and nitric oxide (NO) levels in women with preeclampsia and to find out the relations of diastolic blood pressure with these variables. STUDY DESIGN: We performed a case-control study consisting of randomly selected 34 healthy pregnant women and 35 patients diagnosed as preeclampsia. Lipoperoxidation was ascertained by the formation of MDA. SOD activity was determined by the method of Sun et al. Plasma concentration of NO was estimated using colorimetric assay. Plasma ET-1 and sE-selectin were measured by enzyme-linked immunosorbent assay (ELISA). A nephelometric method for fibronectin quantitation was used. RESULTS: The mean plasma level of MDA was significantly higher and SOD was significantly lower in preeclamptic pregnancies (P<0.001). Plasma concentrations of fibronectin, sE-selectin and ET-1 were significantly increased, whereas NO was significantly decreased in women with preeclampsia than normotensive women (P<0.001). CONCLUSION: Increased plasma levels of MDA, fibronectin, sE-selectin, ET-1, and decreased plasma levels of NO and SOD in preeclamptic patients suggest that poorly perfused fetoplacental unit is the origin of oxygen free radicals and lipid peroxides.     

Endothelial nitric oxide synthase polymorphism in preeclampsia

OBJECTIVE: We wished to determine whether genetic variability in the gene encoding endothelial nitric oxide synthase (eNOS) modifies individual susceptibility to the development of preeclampsia. METHODS: The study involved 132 preeclamptic and 113 healthy control pregnant women who were genotyped for the Glu298Asp polymorphism in the eNOS gene. Chi(2) analysis was used to assess genotype and allele frequency differences between preeclamptic women and controls. RESULTS: A statistically similar allelic distribution of eNOS Glu298Asp polymorphism was observed in the two groups, with the frequency of the variant G allele being 74.6% in the preeclampsia group and 67.7% in the control group (P = .091; odds ratio 1.40, 95% confidence interval 0.95, 2.01). Accordingly, the genotype distribution of the NOS polymorphism in the preeclamptic and control groups was found to be similar (P = .233). CONCLUSION: These genotype data in subjects from eastern Finland were not suggestive of an important contribution of the Glu298Asp polymorphism in the NOS gene on preeclampsia across populations. However, the observed association between the G allele and disease risk, of borderline significance, may imply that other polymorphism(s) in the gene may modify disease risk.     

Calcium, nitric oxide, and preeclampsia

A relationship between calcium dietary intake and incidence of preeclampsia was proposed. In the Andean Ecuadorian population, the average calcium intake, evaluated by a 24 hours dietary recall range between 52.3% of the US RDA to 77%. The calcium intake in women with preeclampsia was significantly lower in relation with normal pregnant women. Three prospective, randomized, double-blind, placebo-controlled clinical trials to investigate the effect of calcium supplementation (2 g/day of elemental calcium) in the incidence of pregnancy-induced hypertension and preeclampsia were conduced between 1984 and 1995. All the subjects included were nulliparous, younger that 25 years old, first prenatal visit before 24 weeks' gestation, residency in Quito, and normotensives. These clinical trials showed a risk reduction in pregnancy induced hypertension and preeclampsia in the calcium group. Calcium supplementation was associated with an increase in the serum ionized calcium concentrations. Moreover, women with preeclampsia showed a significant decrease in the levels of the serum ionized calcium. Ionic calcium is crucial for the synthesis of vasoactive substances in the endothelium as prostacyclin and nitric oxide. Recent results suggest that an alteration in the action of NO may be related to a high inactivation by free radical superoxide, secondary to an inflammatory process.     

Association of endothelial nitric oxide synthase gene G894T polymorphism and serum nitric oxide levels in patients with preeclampsia and gestational hypertension

Objective: Pregnancy-induced hypertension is one of the most important cause of maternal-fetal morbidity and mortality. Pregnancy-related hypertensive disorders are usually associated with diminished nitric oxide (NO) levels. We aimed to evaluate the role of serum NO levels and eNOS gene G894T polymorphism on hypertensive disorders of pregnancy.

Methods: Eighty patients with gestational hypertension or preeclampsia, and 80 healthy pregnants were enrolled to analyze serum NO levels and G894T polymorphism of the eNOS gene. NO level was analyzed by high-performance liquid chromatography (HPLC) method. The G894T polymorphism of the eNOS gene was determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP).

Results: There was no significant difference between groups in terms of G894T/eNOS genotype and allele frequencies (p?>?0.05). Serum NO levels were significantly lower in the patients group. In the control group, subjects with thymine-thymine (TT) genotype had significantly lower NO levels when compared to subjects with guanine-guanine (GG) or guanine-thymine (GT) genotype (p?Conclusions: We failed to demonstrate an association between eNOS gene G894T polymorphism and serum NO levels in patients with pregnancy-induced hypertensive disorders. We established a relation between pregnancy-induced hypertension and low NO levels.     

Cerebrospinal fluid nitric oxide level changes in preeclampsia

OBJECTIVE: The purpose of this study was to determine the level of nitric oxide (NO) metabolites, nitrite and nitrate in human cerebrospinal fluid (CSF) and serum and to assess whether there is any relationship among CSF, serum nitrate-nitrite levels and preeclampsia. STUDY DESIGN: Twenty-one preeclamptic and 27 healthy pregnant women as control group who underwent cesarean section (C/S) were included in the study. Before administering local anesthetic for spinal anesthesia, 2 ml CSF and 4 ml venous blood sample were taken. CSF and serum total nitrite, direct nitrite and nitrate levels were determined spectrophotometrically. RESULTS: CSF total nitrite, direct nitrite and nitrate levels were significantly different between the two groups (21.00+/-1.68, 8.28+/-0.89 and 12.71+/-1.08 micromol/l, respectively versus 15.53+/-1.49, 5.57+/-0.39 and 9.96+/-1.45 micromol/l, respectively, P<0.05). Significantly higher serum nitrate level was found (31.84+/-2.31 micromol/l) in the control group compared to the preeclamptic group serum nitrate level (25.06+/-2.02 micromol/l). Statistical comparisons were performed by the Mann-Whitney U-test. CONCLUSION: CSF-NO is significantly higher but serum NO is lower in preeclamptic group compared with control group may suggest independent regulation of NO in the two compartments. The determination of CSF-NO metabolites could be useful to clarify whether increased NO production is predominantly associated with poor perfusion of the brain in preeclampsia.     

胎盘生长因子与子痫前期发病及一氧化氮关系的研究

目的:探讨胎盘生长因子(PLGF)在子痫前期发病中的作用及其与一氧化氮的关系。方法:选择妊娠期高血压疾病患者45例,其中妊娠期高血压10例,轻度子痫前期12例,重度23例;选择同期正常妊娠妇女20例作为对照组。采用免疫组织化学染色法和逆转录-聚合酶链式反应(RT-PCR)检测两组患者胎盘PLGF蛋白及mRNA的表达。采用硝酸盐还原酶法测定两组胎盘组织NO浓度的变化。结果:(1)免疫组化结果显示,轻度和重度子痫前期的胎盘绒毛合体滋养细胞、绒毛间质PLGF表达均显著低于正常妊娠组(P<0.05),妊娠期高血压组与正常组无差别;PLGF在妊娠期高血压、子痫前期组及正常妊娠组分布范围基本一致,主要分布在绒毛合体滋养细胞和间质细胞胞浆,部分血管合体膜上也有表达;(2)轻、重度子痫前期胎盘组织PLGF mRNA平均灰度分别为3.33±0.39、1.97±0.29,显著低于正常妊娠组的平均灰度4.87±0.60(P<0.01);(3)轻、重度子痫前期胎盘组织中NO浓度分别为8.20±5.56μmol/g、6.46±2.25μmol/g,显著低于对照组18.10±7.12μmol/g(P<0.05);妊娠期高血压组胎盘组织NO浓度与对照组差异无显著性;(4)胎盘组织中胎盘生长因子表达水平与胎盘组织NO浓度呈显著正相关(r=0.54,P<0.05)。结论:子痫前期胎盘组织中胎盘生长因子水平降低,NO浓度下降,可能在子痫前期的发病中起一定作用。     

尿皮素对体外培养的人脐静脉内皮细胞一氧化氮及一氧化氮合酶的影响

目的:通过检测尿皮素(UCN)对人脐静脉内皮细胞(HUVEC)一氧化氮(NO)生成及一氧化氮合酶(NOS)表达的影响,探讨UCN调节胎儿-胎盘血管张力的分子机制。方法:在离体培养的HUVEC中加入不同浓度的UCN(0、0.1、1、10nmol/L)、10nmol/L促肾上腺皮质激素释放激素(CRH)及向以上各组UCN/CRH同时加α-helical-CRH进行体外培养,用硝酸还原酶法检测细胞上清液中NO的水平,蛋白印迹法检测内皮型一氧化氮合酶(eNOS)和诱导型一氧化氮合酶(iNOS)蛋白表达水平的变化。结果:在与UCN共同培养4~8h后,HUVEC细胞上清液中NO水平呈时间和剂量依赖性变化,随着培养时间的延长,UCN浓度增加,NO水平逐渐升高;UCN组HUVEC iNOS表达水平比对照组明显升高(P<0.05),且呈浓度依赖性升高。而各组eNOS表达水平与对照组比较无明显变化(P>0.05)。UCN/CRH α-helical-CRH组HUVEC上清液中NO水平和HU-VEC iNOS表达水平与对照组比较无明显变化,差异无统计学意义(P>0.05),与相同浓度UCN/CRH组比较NO水平和iNOS蛋白表达水平明显降低,差异有统计学意义(P<0.05)。结论:UCN可促HUVEC合成及释放NO,NO生成增多与UCN通过促进肾上腺皮质激素释放激素2β受体(CRH-R2β)正相调节iNOS蛋白表达有关,这可能是UCN调节胎儿-胎盘血管张力的分子机制之一。     

Endogenous inhibitors of nitric oxide and preeclampsia: A review

Nitric oxide (NO) is a potent vasodilator. NO is synthesized by NO synthases (NOS) and NOS are inhibited by asymmetrical dimethylarginine (ADMA). ADMA is metabolized by dimethylarginine dimethylaminohydrolase (DDAH) and excreted in the kidneys. Lower ADMA levels in pregnant women compared to non-pregnant controls suggest that ADMA has a role in vascular dilatation and blood pressure changes. Several studies show an increase in ADMA levels in pregnancies complicated with preeclampsia. Elevated ADMA levels in preeclampsia are seen before clinical symptoms have developed; these findings suggest that ADMA has a role in the pathogenesis of preeclampsia.     

Plasma and placental nitric oxide levels in women with and without pre-eclampsia living at different altitudes

Objective

To investigate the nitric oxide (NO) levels in the plasma and the placentas of pregnant women with pre-eclampsia and women without pre-eclampsia, and to determine the effect of high or low altitude of residence.

Methods

NO was determined by chemoluminescence and group comparisons were performed.

Results

Women with pre-eclampsia (n = 63) had higher plasma NO levels (38.6 ± 17.44 vs 30.6 ± 12.44 µmol/L, P = 0.004) and higher placental NO levels (38.5 ± 17.0 vs 24.3 ± 7.16 ng/mg protein, P < 0.05) compared with women without pre-eclampsia. A similar trend was found when comparisons were made according to altitude of residence. NO levels were significantly higher in the plasma of pre-eclamptic women living at sea level (41.11 ±18.78 vs 28.96 ± 9.57 µmol/L, P = 0.003), and in the placentas of women living at high altitude (39.51 ± 16.98 vs 21.91 ± 6.64 ng/mg protein, P < 0.0001).

Conclusion

Women with pre-eclampsia had higher plasma and placental NO levels and the differences were associated with altitude of residence.     

Plasma nitric oxide metabolites and lipid peroxide levels in preeclamptic pregnant women before and after delivery

The glutathione S-transferases (GSTs) are a family of isoenzymes with several functions. These include the metabolism of endogenous and exogenous toxic compounds, an isomerase activity in steroidogenesis and intracellular transport. This study has used immunohistochemistry to demonstrate the distribution of the three classes of GST (alpha, mu and pi) in the human ovary at different stages of the menstrual cycle. Alpha-GST was found in cells related to steroid hormone production and probably acts as a delta4-5 isomerase. Mu-GST was predominantly found in the non-luteinized stromal cells and its function is obscure. Pi-GST was found in surface 'epithelial' inclusions and the media of arteries where it is thought to play a detoxifying role.     

Endogenous inhibitors of nitric oxide and preeclampsia: a review.

Nitric oxide (NO) is a potent vasodilator. NO is synthesized by NO synthases (NOS) and NOS are inhibited by asymmetrical dimethylarginine (ADMA). ADMA is metabolized by dimethylarginine dimethylaminohydrolase (DDAH) and excreted in the kidneys. Lower ADMA levels in pregnant women compared to non-pregnant controls suggest that ADMA has a role in vascular dilatation and blood pressure changes. Several studies show an increase in ADMA levels in pregnancies complicated with preeclampsia. Elevated ADMA levels in preeclampsia are seen before clinical symptoms have developed; these findings suggest that ADMA has a role in the pathogenesis of preeclampsia.