Prostaglandin D2 release by endometrium and myometrium

Prostaglandin D2 (PGD2) release was studied using a superfusion technique in endometrium and myometrium obtained at hysterectomy from 36 women with measured menstrual blood loss (range 4-840 ml). PGD2 was produced by both tissues with greater rates from endometrium. Cyclical changes in release were found only in the endometrium with increased rates during menstruation and the mid-luteal phase. In the myometrium the highest release rates were present during menstruation at the start of the superfusion. No significant correlation was found between menstrual blood loss and endometrial or myometrial PGD2 release.     

Primary and myoma-associated menorrhagia: role of prostaglandins and effects of ibuprofen

Summary. The release of 6-keto-prostaglandin F_1α(6-keto-PGF_1α), a metabolite of prostacyclin (PGI₂) and thromboxane B2 (TxB2), a metabolite of thromboxane A2 (TxA2), was estimated in endometrial biopsies taken from 12 menorrhagic and 12 healthy women during the luteal phase of the cycle. The releases of 6-keto-PGF_1α and TxB2 were normal, but the ratio TxB2/6-keto-PGF_1α was inversely related to menstrual blood loss in women with measured menstrual blood loss exceeding 70 ml. In the second part of the study, 24 women with excessive menstrual bleeding (13 with primary menorrhagia, 10 with uterine fibro-myomas, one with haemostatic factor VIII deficiency) were treated at random with ibuprofen (600mg/day and 1200mg/day) and with a placebo. Ibuprofen 1200 mg/day reduced (P<0.01) median blood loss from 146 ml (range 71–374 ml) to 110 ml (30–288 ml) in primary menorrhagia but had no effect on blood loss in women with uterine fibroids and factor VIII deficiency. Blood loss was normal in six women and was not affected by ibuprofen. Thus, our data suggest that there is a PGI₂ dominance in the endometrium of patients with menorrhagia. In addition, primary, but neither fibromyoma nor coagulation defect-associated menorrhagia, can be treated by ibuprofen.     

Lack of effect of circulating prostacyclin on contractility of the non-pregnant human uterus

Summary. To study the effect of prostacyclin (PGI₂) on the contractility of the non-pregnant human uterus, the intrauterine pressures in the isthmus and fundus of the uterus were recorded before, during and after intravenous PGI₂ at different phases of two consecutive menstrual cycles in eight women. Infusions of 1–8 ng of PGI₂ mur⁻¹ kg⁻¹ for 20 min caused no changes in intrauterine pressure either during menstruation or any other phase of the cycle when compared with the contractility patterns in the same woman during the control infusion. Thus these data suggest that circulating PGI₂ is not involved in regulating the contractility of the non-pregnant human myometrium.     

Vaginal and abdominal delivery increases maternal urinary 6-keto-prostaglandin F1α excretion

Summary. To study the role of the antiaggregatory and vasodilatory prostacyclin (PGI₂) during human delivery, serial urine samples collected from 13 women delivered vaginally and from eight delivered abdominally were assayed for 6-keto-prostaglandin F_1α (6-keto-PGF_1α a breakdown product of PGI₂) by high-performance-liquid-chromatography and radioimmunoassay. In women delivered vaginally the mean urinary 6-keto-PGF_1α concentration was 41.9 (SE 8.3) ng/mmol creatinine, before the onset of labour and increased progressively to a maximum of 186.5 (SE 47.6) ng/mmol creatinine 2 h after delivery irrespective of the use of oxytocin and epidural analgesia. In women delivered by caesarean section under epidural anaesthesia, the urinary 6-keto-PGF_1α rose from 33.4 (SE 4.2) ng/mmol creatinine to 2153 (SE 314) ng/mmol creatinine 2 h after section. In both groups the increased levels had fallen by 24 h postpartum to levels below those found before delivery. In neonatal urine 6-keto-PGF_1α concentrations were some 12–30 times higher than those in postpartum urine. Thus, vaginal and abdominal delivery is accompanied by significant increases in maternal PGI₂ release, perhaps in the myometrium and/or intrauterine tissues. This may be of significance in the regulation of fetoplacental blood flow and in the prevention of intra- and postpartum thrombosis.     

Effect of vacuum curettage on the concentrations of plasma 6-keto-prostaglandin Flα and serum thromboxane B2

Summary. Serial plasma samples collected before and after vacuum curettage followed by methylergometrine injection in 10 women were assayed for 6-keto-prostaglandin F_lα (6-keto-PGF^1α). The mean 6-keto-PGF_lα concentration was 97.2 (SE 8.8) pg/ml before cervical dilatation. The concentration rose to 128.2 (SE 13.5) pg/ml (P < 0.10) immediately and to 133.3 (SE 17.8) pg/ml (P < 0.05) 1 h after curettage and returned to the initial value within 5 h. Neither methylergometrine nor anaesthesia, nor non-gynaecological surgery, caused changes in the level of plasma 6-keto-PGF_lα. The capacity of the platelets to produce thromboxane A² during spontaneous clotting of blood did not change during vacuum curettage, anaesthesia and non-gynaecological surgery, nor after methylergometrine. The evidence suggests that the pregnant myometrium and/or intrauterine tissues capable of generating prostacyclin (PGI₂) in vitro may release PG1₂ also in vivo .     

The actions of prostaglandins and their interactions with angiotensin II in the isolated perfused human placental cotyledon

Summary. The prostaglandins PGE₁, PGE ₂, PGD ₂, PGF _2α., U46619 and 6_β-PGI_l were administered as bolus injections both separately and in combination with angiotensin II into the fetal circulation of isolated human placental cotyledons perfused in vitro . PGF_2α, and PGD₂, caused small dosedependent increases in fetal perfusion pressure when compared with U46619 which acted as an extremely potent vasoconstrictor of the fetal-placental vasculature. PGE₁, caused very small dose-dependent decreases in fetal perfusion pressure when injected on its own. In combination with angiotensin 11, PGE₁, PGD₂, and 6_β-PG1₁, caused significant, dose-related attenuations of the angiotensin II vasoconstrictive response whereas PGE₂, PGF_2α, and U46619 potentiated the response. Injections of angiotensin II after the infusion of indomethacin into the fetal circulation resulted in a potentiation of angiotensin II induced vasoconstriction. The results indicate that prostaglandins exert their effects on the fetal-placental circulation by modulating the actions of angiotensin II.     

The actions of prostaglandins and their interactions with angiotensin II in the isolated perfused human placental cotyledon

Summary. The prostaglandins PGE₁, PGE ₂, PGD ₂, PGF _2α., U46619 and 6_β-PGI_l were administered as bolus injections both separately and in combination with angiotensin II into the fetal circulation of isolated human placental cotyledons perfused in vitro . PGF_2α, and PGD₂, caused small dosedependent increases in fetal perfusion pressure when compared with U46619 which acted as an extremely potent vasoconstrictor of the fetal-placental vasculature. PGE₁, caused very small dose-dependent decreases in fetal perfusion pressure when injected on its own. In combination with angiotensin 11, PGE₁, PGD₂, and 6_β-PG1₁, caused significant, dose-related attenuations of the angiotensin II vasoconstrictive response whereas PGE₂, PGF_2α, and U46619 potentiated the response. Injections of angiotensin II after the infusion of indomethacin into the fetal circulation resulted in a potentiation of angiotensin II induced vasoconstriction. The results indicate that prostaglandins exert their effects on the fetal-placental circulation by modulating the actions of angiotensin II.     

Immunohistological localization of pregnancyassociated endometrial α2-globulin (α2-PEG) in endometrial adenocarcinoma and effect of medroxyprogesterone acetate

Summary. Endometrium from postmenopausal women with endometrial adenocarcinoma was examined immunohistochemically using a monoclonal antibody to pregnancy-associated endometrial α₂-globulin (α₂-PEG), the major secretory protein of the glandular epithelium during the late luteal phase of the menstrual cycle and early pregnancy. Specimens were obtained at initial diagnostic curettage and at hysterectomy after medroxyprogesterone acetate (MPA) therapy. α₂-PEG was not detected in any malignant tissue irrespective of histological differentiation. Non-malignant endometrium obtained in association with malignant tissue was negative for α₂-PEG before treatment although after MPA therapy all specimens obtained exhibited marked α₂-PEG localization in glands. In four specimens endogenous alkaline phosphatase was observed consistently only in the malignant endometrium. Malignant endometrium does not appear to synthesize α₂-PEG nor is its synthesis induced by an oral progestogen, so that it does not represent a useful marker for endometrial carcinoma. Non-malignant endometrium in postmenopausal women appears to be fully capable of α₂-PEG production after stimulation with an oral progestogen.     

Topographical distribution of prostaglandin E receptors in human myometrium

Summary. The binding of radiolabelled prostaglandin (PG) F_2α and PGE₂ by human myometrium was measured in vitro and the distribution and characteristics of the binding sites in non-pregnant and pregnant uteri were studied. PGF_2α binding sites were of low affinity (Kd 30 nM) and could be occupied by PG of the E series with higher affinity than PGF_2α itself. PGE binding sites were of high affinity (Kd 1·5 nM) and highly specific for PG of the E series, suggesting that they represent true PGE receptors. The concentration of PGE receptors was higher in nonpregnant than in pregnant uteri at term. In non-pregnant uteri the concentration of PGE receptors was highest in the fundus and decreased towards the cervix; in term pregnant uteri the concentration was constant in all areas. In both non-pregnant and pregnant uteri there was a significantly lower PGE binding affinity in cervix than in myometrium from the fundus-corpus area. The concentrations and affinity of PGE receptors were similar during the proliferative and secretory phases of the menstrual cycle and were not influenced by age of the patient. PGE receptors were not influenced by the presence or absence of primary dysmcnorrhoca but appeared to be increased in unexplained menorrhagia.     

Are leukotrienes involved in human uterine contractility?

Summary. The effects of leukotrienes (LT) on the contractility of human and rat myometrial strips in vitro were compared with the effects of prostaglandins (PGs) and oxytocin. Preparations of human myometrial membranes were investigated for the presence and characteristics of LTC₄ receptors. Neither the peptido-leukotrienes (LTC₄, LTD₄, LTE₄) nor LTB₄ had any consistent effect, stimulatory or inhibitory, on human pregnant or non-pregnant myometrium, at doses up to 1·25 μM; nor did they have any effect in rat non-pregnant myometrium. As expected, PGE₂, PGF_2α (0·3 μM) and oxytocin (5 nM) stimulated human pregnant myometrium. PGF_2α stimulated and PGE₂ inhibited human non-pregnant myometrium but oxytocin had no effect; all three compounds stimulated rat non-pregnant myometrium. The binding of ³H-LTC₄ to human myometrium was specific (LTC₄> LTD₄ >>> LTE₄, LTB₄, PGE₂, PGF_2α, arachidonic acid) but of low affinity compared with the binding of ³H-PGE₂ to the same membrane preparations. These data support the view that leukotrienes have little direct influence on myometrial contractility.     

Fibrinogen-fibrin degradation products in menstrual blood from women with normal and excessive menstrual losses.

Fibrinogen-fibrin degradation products, FDP, in menstrual blood during the first three days of menstrual blood during the first three days of menstruation have been investigated. Two groups of women were studied, those with normal menstrual blood loss (15 women, mean loss 30 ml, range 8-60 ml) and those with menorrhagia (14 women, mean loss 222 ml, range 107-729 ml). The following results were obtained: 1). The FDP concentrations decreased during menstruation in both groups. 2). The FDP concentrations in the two were compared for each day of the menstrual period. No differences were found between the two groups. A possible explanation of the results is given: there is a higher rate of coagulation and fibrinolysis in the endometrium of women with menorrhagia compared with women with normal blood losses. The hypothesis is supported by results of studies in which tranexamic is supported by results of studies in which tranexamic acid, an inhibitor of fibrinolysis, was given to reduce the menstrual blood loss. 3). The FDP excretion patterns differed from women to women. There were no consistent differences between the menorrhagic and the control group.     

Menstrual effluent in endometriosis shows no difference in volume, VEGF-A, MMP2 and MMP9 or sFLT

Since retrograde menstruation is considered a key event in the aetiology of endometriosis, this study sought to determine whether the menstrual effluent of women with this condition is different from that of those with a normal pelvis. As the amount of blood lost during menstruation is thought to be higher in this group, measured objective menstrual blood loss (MBL) was measured. In addition, factors enhancing both ectopic implantation of endometrium and its subsequent growth (by establishing a neo-vasculature) were chosen for study. Our hypothesis was that they are increased in the menstrual effluent of women with endometriosis. The study showed that at the time of menstruation, there is no difference in MBL or in the volume of menstrual effluent between women with endometriosis and those with a normal pelvis at laparoscopy. In addition, vascular endothelial growth factor-A (VEGF-A) message and protein, soluble truncated receptor sVEGF-R1 (sFLT), matrix metalloproteinase (MMP) 2 and MMP9 activities were also shown to be similar between the two groups. It is concluded that the enhanced expression of VEGF-A and MMP in the peritoneal fluid and ectopic lesions of endometriotic patients may be a secondary event, resulting from an innate difference in peritoneal and systemic factors rather than in the endometrium, causing an abnormal peritoneal response to menstrual debris and facilitating its ectopic implantation.     

Phospholipase activity in the endometrium of women with normal menstrual blood loss and women with proven ovulatory menorrhagia

Summary. The activity of phospholipase A ₂ types 1 and 2 and phospholi-pase C was measured in the endometrium of women with ovulatory menorrhagia and in those with normal menstrual blood loss. In both groups of subjects phospholipase A ₂ type 1 activity was significantly higher in the secretory phase than in the proliferative phase (   P < 0.001  ). The median activity (pmol/mg protein/min) for the proliferative phase was 27–6 in normal subjects and 40–4 in women with ovulatory menorrhagia and for the secretory phase the median activity was 144–5 in normal women and 138–1 in women with ovulatory menorrhagia. There was no difference between the two groups of women at either stage of the cycle. Phospholipase A ₂ type 2 activity was also higher in the secretory phase than in the proliferative phase (   P < 0.05  for normal subjects and   P < 0.001  for women with menorrhagia). The median activity (pmol/mg protein/min) for the proliferative phase was 94–4 (normal subjects) and 56–6 (women with menorrhagia) and for the secretory phase 148–3 (normal subjects) and 142–5 (women with menorrhagia). The activity of phospholipase A ₂ type 2 was significantly lower in the proliferative phase of women with ovulatory menorrhagia compared with normal subjects (   P < 0.05  ). Phospholipase C activity (nmol/mg protein/min) was significantly higher in women with ovulatory menorrhagia (median 8-2) compared with women with normal blood loss (median 5–5) (   P < 0.01  ).     

A functional study of platelets in menstrual fluid

Platelets were isolated from menstrual and peripheral venous blood samples taken from nine women during the first 2 days of menstruation. The washed platelets were tested for their ability to aggregate in response to arachidonic acid, ADP, and collagen, and to metabolize arachidonic acid. Menstrual platelets differed from venous platelets in (1) failing to aggregate when challenged with aggregatory stimuli and (2) producing no appreciable cyclo-oxygenase products from arachidonic acid as reflected in thromboxane B2 release. However, incubation of peripheral venous platelets with menstrual serum obtained from the same patients induced aggregation. The responses of menstrual and peripheral venous platelets were the same irrespective of the patients' total menstrual blood loss. Uterine venous platelets collected during menstruation from two patients at hysterectomy aggregated normally and produced thromboxane B2.     

The effects of metabolic inhibition on intracellular calcium and contractility of human myometrium

Objective Hypoxia occurs in the uterus during labour and may contribute to dysfunctional labours. We wanted to establish its effects on pregnant human myometrium and elucidate the mechanisms involved.
Design Scientific study.
Setting University Hospital and laboratories.
Population or Sample Term pregnant women.
Methods We measured contractions and intracellular [Ca²⁺] ([Ca²⁺]_i), in biopsies from term pregnant women undergoing elective caesarean section, and used cyanide to block oxidative phosphorylation.
Main outcome measures Changes in contractility and calcium.
Results Although basal levels of [Ca²⁺]_i and tone rose, spontaneous and agonist-induced Ca²⁺ transients and phasic contractions were rapidly reduced and abolished by cyanide. Neither stimulation of the uterus with oxytocin nor the Ca channel agonist, Bay K8644, prevented the changes produced by cyanide. The tonic force produced by depolarising the myometrium was also decreased by cyanide, but slowly recovered towards control levels, whereas [Ca²⁺]_i was maintained throughout. Similar data were obtained when nitrogen, rather than cyanide, was applied to the depolarised uterus.
Conclusions Impairment of oxidative phosphorylation is a potent depressor of phasic activity in human myometrium, irrespective of how it is produced, and our data suggest its effects lie at and beyond the surface membrane. Stimulation of the hypoxic uterus was not effective, which may explain the unpredictability of oxytocin application in some dysfunctional labours.     

Normal range of fetal transcutaneous carbon dioxide tension during labour

Summary. Fetal transcutaneous carbon dioxide tension (tc-Pco), was monitored during 122 deliveries, using an electrode temperature of 44°C in 80 cases and of 41°C in 42 cases. Significant correlations between tc- P co₂ and umbilical artery blood P co₂ were found using both electrode temperatures, but the regression lines indicated a larger and more inconstant CO₂-contribution from skin metabolism when the low electrode temperature was used. Normal range of tc- P co₂ was calculated at 41°C and 44°C electrode temperatures. Mean values of fetal tc- P co₂ were found to increase during normal labour, and especially in fetuses developing acidosis, but only four of six infants born with acidaemia had tc- P co₂ values exceeding the normal range.     

Production of prostacyclin, 6-keto-PGFlα and thromboxane B2 by human umbilical vessels increases from the placenta towards the fetus

Summary. The aim of this study was to investigate the production of prostacyclin (PGI₂) and thromboxane B₂ (TXB₂) by incubated samples of umbilical arteries and veins taken at different distances (2, 10,20,30 cm) from the placenta to provide additional information relevant to the haemodynamics of umbilical blood flow. The production of PGI₂, and 6-keto-PGF_1α (the stable metabolite of PGI₂), was higher in both veins and arteries as the distance from the placenta at which the vessels were sampled was increased. A similar correlation between production by venous rings and distance from the placenta was observed for TXB₂, but there was no apparent gradient of TXB₂ production by the samples of arterial rings. No statistically significant variations were discernible in the ratio of 6-keto-PGF_1α:TXB₂ (∼50 in the veins and ∼20 in the arteries) in relation to the sampling distance. The significance of these high ratios is discussed in relation to umbilical blood flow and fetal well-being and development.     

Determinants of umbilical cord arterial 8-iso-prostaglandin F2alpha concentrations

Objective To determine the concentration of 8-isoPGF_2α in cord blood as a measure of oxidative stress during labour, and to compare them with other established parameters of in vivo lipid peroxidation and with the acid-base status of the newborn.
Method Umbilical cord arterial and venous blood samples were collected from 81 singleton term deliveries for determination of 8-isoPGF_2α, malondialdehyde and organic hydroperoxides. In addition, metabolites derived from the oxidative metabolism of purines during hypoxia-reoxygenation and routine cord blood of oxygen saturation, pH, pO₂, pCO₂, HCO₃ and base excess were measured.
Results Arterial concentrations of 8-isoPGF_2α were significantly higher in cases with fetal distress, tight nuchal cord (   P < 0.001  ), the umbilical coiling index, and male sex (   P < 0.05  ) (R²= 0.48). No correlation was found with any parameter of acid-base status. In arterial and venous blood the concentrations of organic hydroperoxides and hypoxanthine significantly correlated with the fetal nuchal cord (   P < 0.001  ) (R²= 0.26 and 0.16, respectively).
Conclusion Our findings indicate that 8-isoPGF_2α in cord arterial blood is a suitable parameter to quantify a possible oxidative stress in the fetus during labour. Measurements of the F₂-isoprostane concentrations in cord blood at labour provide a clinically useful method to assess the perinatal outcome.     

Comparison of pregnancy-specific β1-glycoprotein (SP1) and ultrasound in predicting the date of delivery

Summary. The accuracy of ultrasound measurements (crown-rump length and gestational sac diameter) and the serum concentration of pregnancy-specific β₁-glycoprotein (SP₁) in the prediction of the date of birth was analysed in a study population of 94 patients. When measured before 8 weeks after the last menstrual period (LMP) the serum concentration of SP₁, was found to be a good predictor of the expected date of delivery and a good alternative to ultrasound, but it was of limited use when determined at a later gestation.     

Involvement of prostaglandins in vasopressin stimulation of the human uterus

The involvement of prostaglandins (PG) in the vasopressin (VP) action on the human uterus was investigated in healthy women during three menstruations. Intrauterine pressure was recorded and total pressure area measured. Repeated plasma samples were taken for estimations of arginine(A)- and lysine(L)-VP, 15-keto-13,14-dihydro-PGF_2α and 11- ketotetranor PGF metabolites. During the first menstruation LVP was infused in a dose of 0.08 μg/min. During the second menstruation the infusion of LVP was repeated with the same dose, but 70 min before infusion the women received an oral dose of 500 mg of naproxen. During the third menstruation PGF_2α was administered intravenously in a dose of 25 μg/min. LVP infusion per se caused a significant increase in uterine activity and plasma levels of LVP and PG metabolites. When the women were pretreated with naproxen practically the same uterine activity was induced and closely similar plasma levels of LVP were obtained, but the levels of PG metabolites decreased significantly in comparison with the first series of experiments. Infusion of PGF_2α caused an increase in uterine activity but no change in the plasma levels of AVP. The results indicate that uterine stimulation with VP is possible without an obligatory last step of PG synthesis and release. The results also support the concept that an elevated VP level in primary dysmenorrhoea may be of aetiological importance and is not just released as a 'stress'-hormone because of the dysmenorrhoeic pain.