Journal of Obstetrics and Gynaecology (2001) Vol. 21, No. 5, 546– 549

ISSN 01 44– 3615 print/ISSN 1364– 68 93 online/01/050546– 0 4 ã Taylor & Francis Limited, 2001DOI: 1 0.10 80/0144361 012007 3972

Abstracts from oral presentations to the Blair BellResearch Society meeting held at St Mary’s Hospital,London on 21 September 2000

A role for gap junction communication inmediating EDHF-type responses in myometrialarteries from normal pregnant women

LOUISE KENNY,1 W. DUNN, 2 M. RANDALL,2

D. KENDALL,2 and P. BAKER,1

1School of Human Development and 2School ofBiomedical Sciences, University of Nottingham,Nottingham, UK

Introduction . We have reported previously that endothelium-depend -ent relaxation in myometrial resistance arteries isolated from normalpregnant women is independent of nitric oxide and prostanoids, butis sensitive to partial depolarisation, suggesting the involvement ofan endothelium-derived hyperpolarising factor (EDHF). Recent stud-ies have provided evidence that EDHF-type responses are dependentupon functional gap junctions. We sought to investigate whether theEDHF-type relaxation observed in myometrial resistance arteries innormal pregnancy involves gap junction communication.

Methods . Myometrial biopsies were obtained from healthypregnant women undergoing elective caesarean section at term(n=24). Myometrial resistance arteries <400 mm in diameter weredissected and mounted on a pressure myograph. Following equi-libration, the vessels were constricted to approximately 50% oftheir original resting diameter with incremental amounts of thethromboxane mimetic, U46619. Concentration-depende nt re-laxations to the endothelium-dependent vasodilator, bradykinin,were measured in the presence of nitro-L-arginine methyl ester(L-NAME) [100 mM[ and indomethacin [10 mM[ to inhibit nitricoxide and prostanoid production, respectively. Following washing,the constriction and concentration response curves were repeatedin a variety of inhibitors of gap junctional communication;18aglycyrrhetinic acid (18aGA) [100 mM[, carbenoxolone [10mM[, palmitoleic acid [50 mM[ and SR141716A [10 mM[.

Results. Bradykinin induced a concentration dependent relaxa-tion in myometrial resistance arteries that was independent ofnitric oxide and prostanoids. Inhibitors of gap junction communi-cation significantly attenuated the relaxation induced by bradykinin.

Control Emax 81·2 (±5·9%) 18aGA Emax 6·0 (±2·9%)*Control E

max 77·4 (±7·0%) carbenoxolone E

max 17·7 (±7·3%)*

Control Emax 82·2 (±6·7%) palmitoleic acid Emax 9·2 (±3·6%)*Control E

max 79·4 (±8·4%) SR141716A E

max 12·2 (±8·0%)*

*P<0·01

Conclusion. This is the first study to provide evidence that gapjunction communication is essential for EDHF-type relaxation inmyometrial resistance arteries in normal pregnancy.

The presence of an area of fetal membranesoverlying the lower uterine segment exhibitingmorphological changes and myofibroblastactivation is characteristic of fetal membranesobtained prior to the onset of labour at term

P. C. McPARLAND, D. J. TAYLOR andS. C. BELLPreterm Birth Research Group, Department of Obstetricsand Gynaecology, Faculty of Medicine and BiologicalSciences, University of Leicester, Leicester, UK

A zone of altered morphology of the fetal membranes has beendescribed within a restricted area of the rupture line following

spontaneous delivery a t term. The key features of this zonewere increased thickness of the connective tissues of the amnionand chorion, thinning of the cytotrophoblastic and maternaldecidual layers and myofibroblast activation within cells of thechorionic connective tissue, as defined by expression of smoothmuscle actin (SMA). In this study we have examined fetal mem-branes from elective caesarean sections before the onset oflabour at 38–39 weeks (n=10) to determine the presence anddistribution of such features. In all patients a region exhibitingthese features was localised in membranes mapped to the lowersegment of the uterus, and was consistent with being centred overthe internal os of the cervix. However, within patients, the di-ameter of the region affected by the individual features varied:(1) Reduction in decidual layer thickness to less than 50_m, 6–21 cm. (2) Thinning of cytotrophoblast layer, in some casesdown to 1–2 cell layers in thickness , up to 9 cm. (3) Increasedthickness of the connective tissue layers, 6–15 cm. (4) Expres-sion of SMA, 9–15 cm. Two patients also expressed SMA in thefibroblast layer in the same region. The presence of this regionoccurred in all patients prior to the onset of labour, with thevirtual absence of the cytotrophoblast layer and presence ofactivated myofibroblasts within the chorionic connective tissue.

This has functional implications for differential anatomicalparacrine relationships with the underlying myometrium, and forprogramming of the rupture of the fetal membranes .

The placenta causes dysfunctional labour

A. WEEKSJessop Hospital for Women, Sheffield S3 7RE

Primary dysfunctiona l labour (PDL) remains a major problem inobstetrics, affecting 25% of nulliparous labourers accounting for20% of caesarean sections (CS). The cause of PDL has never beenelucidated, although its frequent response to oxytocin infusion sug-gests an abnormality of myometrial contractility. Ultrasoundstudies of the third stage of labour show that placental detachmentis dependent on contraction of the retroplacental myometrium.Women with retained placentas exhibit contractile failure in thisarea. This contractile failure is likely to have occurred throughoutlabour and may account for the association of retained placentawith dysfunctional labour.

Figure 1. Percentage change (mean±SEM) in myometrial thicknessduring contractions (R=retroplacental, E=extraplacental).

J O

bste

t Gyn

aeco

l Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Uni

vers

itat d

e G

iron

a on

11/

21/1

4Fo

r pe

rson

al u

se o

nly.

Blair Bell Research Society 547

To explore this relationship regional variations in myometrialcontractility were assessed ultrasonograph ically in two groups ofwomen, 10 with PDL and 10 in normally progressing labour. Themyometrial thickness was measured between and during contractionsin the retroplacental and the extraplacental myometrium. Themean increase (± SEM) in thickness in those women labouring nor-mally was similar in the retroplacental (14·6%±7·5) andextraplacental myometrium (19·5%±10·5; P>0·05). In those withPDL the extraplacental myometrium contracted normally(12·5%±5·6) while there was a thinning of the retroplacental myo-metrium (-9·5%±6·6, P<0·01) (Figure 1).

In women with PDL, the placenta appears to locally inhibitmyometrial contractility. This probably occurs through the produc-tion of a locally active tocolytic factor whose identity is unknown .

MMP-1 , 3, their activity regulators TIMP-1,PAI-1 and tPA do not exhibit anatomicalregional differences in term fetal membranes,prior to labour

J. McLAREN, D. J. TAYLOR and S. C. BELLDepartment of Obstetrics and Gynaecology Universityof Leicester, Leicester, UK

Matrix metalloproteinases (MMPs) mediate matrix degradation, andprevious work has shown elevations in the amount of pro-MMP-9in membranes overlying the lower uterine pole, prior to labour andits subsequent activation during labour/delivery. The aim of this studywas to extend this work and evaluate whether other key membersof the MMP family including MMP-1, 3, the MMP inhibitor TIMP-1 and the regulating molecules of the activator plasmin, tPA andPAI-1, are also regionally altered in term fetal membranes, prior tolabour. Fetal membrane samples, overlying the cervix (lower uter-ine pole), adjacent to the placenta (peri-placental) and mid-way(mid-zone) between these areas were obtained at elective caesareansection (38–39 weeks’ gestation, n=12). MMPs were identified bygel zymography and protein localised by immunohistochemicalstaining. Protein concentrations of pro-MMP-1, 3, TIMP-1, tPAand PAI-1 were assessed by enzyme linked immunoabsorbant assays(ELISA). Gel zymography detected only pro-forms of MMP-1 and3 in the three regions sampled and subsequent ELISA measurement srevealed no regional difference in their concentrations. The valuesfor pro-MMP-1 throughout the membrane were 10·2±7·7 ng/mg and15·5±11·7 ng/mg for pro-MMP-3. The regulators of MMP activityTIMP-1, PAI and tPA, also failed to exhibit regional differences andwere found at concentrations of 22±16 ng/mg, 79±34 ng/mg and5·7±5·18 ng/mg, respectively. Immunohistochemical staining forMMP-1, 3, TIMP-1, PAI-1 and tPA-1 showed proteins localised inthe amniotic epithelium, connective tissue mesenchym, cytotro-phoblast and decidual cells. The presence of these pro-MMPs andtheir activity regulators suggests fetal membrane have the potentialfor co-ordinated extracellular matrix degradation.

A randomised study of total and subtotalhysterectomy: effect on bladder, bowel andsexual function

RANEE THAKAR, I. MANYONDA,S. STANTON, P. CLARKSON,1

SUSAN AYERS and GILL ROBINSON1

Urogynaecology Unit St George’s Hospital, London and1Mayday University Hospital, Croydon UK.Aims. To evaluate prospectively the effect of total (TAH) and sub-total (STAH) hysterectomy on bladder, bowel and sexual function.

Methods. Women having a hysterectomy for benign conditions andwho gave informed consent were were randomised by computer intoTAH or STAH. Both the patient and investigator remained blinded tothe type of hysterectomy for 12 months. Validated questionnaires onbladder, bowel and sexual function and urodynamic studies were car-ried out preoperatively and 6 and 12 months post-hysterectomy.

Results. To date, of the 323 women recruited, data has beenanalysed on 199 women who completed the 12-month follow-up(108 TAH, 91 STAH). No difference was found preoperatively in

baseline measures of urinary and bowel function. Stress inconti-nence was reported by 10% of women but proven to be genuinein only 2%. In the TAH group, stress incontinence was signifi-cantly reduced (P<0·01) at 6 months but not at 12 months. Inboth groups, frequency of micturition was significantly reduced at6 months but persisted only in the TAH group at 12 months(P<0·01). One year postoperatively women who had TAH re-ported less frequent intercourse (P<0·005) than women withsubtotal hysterectomy and more women with TAH reported deepdyspareunia though this failed to reach significance. No differencewas found between the two groups in bladder and bowel symptomsor urodynamic tests.

Conclusions . This is the first randomised prospective study toevaluate subjectively and objectively the effect of bladder func-tion after TAH and STAH. STAH does not appear to confer anybenefits over TAH in respect to bowel and bladder function. Re-moval of the cervix is associated with less frequent intercourseand more dyspareunia. The results of further analysis regardingmorbidity after STAH or TAH is currently under way. This infor-mation may be crucial in counselling and determining the mostappropr iate approach to the most common major gynaecologi-cal operation.

p53 codon 72 polymorphism and risk ofvulval neoplasia

A. N. ROSENTHAL, A. RYAN DEBORAHHOPSTER, T. SURENTHERAN andI. J. JACOBSGynaecology Cancer Research Unit, St. Bartholomew’sand the Royal London Hospitals Medical College, WestSmithfield, London, UK

Recent in vitro functional data suggests that the arginine encod-ing polymorphism at codon 72 of the p53 tumour suppressorgene is more susceptible to degradation by oncogen ic humanpapillomavirus (HPV) E6 protein than the proline polymor-phism. Preliminary epidemiological data found that women withcervical cancer were more likely to be homozygous for argininethan healthy controls. As VIN and vulval squamous cell carci-noma are also HPV-associated, we hypothes ised that womenhomozygous for the arginine polymorphism might be at increasedrisk of developing these diseases. We investigated this polymor-phism in 52 women with HPV-associated vulval cancer, 48 withVIN and 246 ethnically matched healthy controls. HPV detectionwas performed using polymerase chain reaction (PCR) with con-sensus primers and agarose gel electrophoresis. The presence ofoncogenic HPV types was confirmed using direct sequencing ofthe product . p53 polymorphism analysis was performed usingPCR with allele-specific primers and autoradiography. There weresignificant differences in the proportions of the three p53 codon72 genotypes (arginine homozygotes, proline homozygotes andheterozygotes) for both vulval cancer vs. controls (P=0·0023) andfor VIN vs. controls (P<0·0001). These differences resulted froma lower frequency of arginine homozygo tes in both the vulvalcancer group (42%) and the VIN group (29%) compared with thecontrol group (63%). We conclude that the arginine polymor-phism may confer protection against the development ofHPV-associated vulval neoplasia.

The effect of withholding exogenous FSH ongranulosa cell activity, apoptosis and oocytefunction in women undergoing controlledovarian hyperstimulation (COH) for IVF/ICSI

A. TOZER,1,2 C. M. Y . WILSON,2 R. ILES,1

T. AL-SHAWAF,2 A . M. L. LOWER2 andJ. G. GRUDZINSKAS2

1The Williamson Laboratory and2 Fertility Centre, StBartholomew’s and the Royal London School ofMedicine and Dentistry, London, UK.

J O

bste

t Gyn

aeco

l Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Uni

vers

itat d

e G

iron

a on

11/

21/1

4Fo

r pe

rson

al u

se o

nly.

548 Blair Bell Research Society

Introduction . The aim of this study was to assess the effect of with-holding exogenous FSH on the function of populations of granulosacells obtained from individual, different-sized follicles and oocytesin women undergoing COH.

Materials and methods. Women undergoing COH for IVF/ICSIwere recruited prior to oocyte retrieval if: FSH injections had beenwithheld to prevent OHSS (Group A) or a ‘normal’ response wasseen on ultrasound (Group B, acting as a control). At oocyteretrieval, 4–6 follicles of varying size were randomly selected,measured in two dimensions and aspirated. Luteinised granulosa cellswere isolated from the individual follicles, counted and viabilitychecked. Apoptosis studies were performed using a cell deathELISA detection kit.

Results . Follicular aspirates (n=423) were obtained from 79women (33 Group A, 46 Group B). Follicle size-dependent dif-ferences were observed in the oocyte retrieval rate between thetwo groups, more oocytes being retrieved from follicles of 16–25 mm in diam in Group B (82·9% vs. 64·5%, P<0·005). InGroup B, the fertilisation rate increased as the follicle size in-creased. This trend was reversed in Group A, with the highestfertilisation rate being observed in the smaller follicles. In bothgroups the median cell number was greater in the presence of anoocyte (Group A, 180 000 vs. 160 000; Group B, 180 000 vs.150 000) with this difference being greatest in those follicles<16 mm in Group B and in those follicles >25 mm in Group A.Both groups showed a trend towards a lower apoptot ic rate infollicles of 16–25 mm. A lower apoptotic rate was observed inGroup A in the presence of an oocyte (20·4 [IQR: 11·8–35[ vs.29·3 [IQR 21·2–44·4[ P<0·05) but this was not observed inGroup B.

Conclusions . Withholding exogenous FSH in women at risk ofOHSS has a significant, follicle size-dependent effect on oocyteretrieval and fertilisation. Follicle size-dependent differences ingranulosa cell numbers and apoptotic rates in relation to oocyteretrieval may help in our understanding of the pathophysiologyof OHSS.

Sources of serum inhibin-A and pro-alpha-C inearly pregnancy

SOMA LAHIRI, TINA ANOBLE,P. S. STEWART and W. L. LEDGERCentral Sheffield University Hospitals, Sheffield, UK

Introduction . In early pregnancy the majority of circulating InhibinA is thought to originate from the fetoplacental unit and Inhibinpro-alpha-C is secreted from the corpus luteum. Betterunderstanding of the regulation of expression of these proteinswould be useful in understanding implantation and early pregnancyfailure.

Material and methods. We have studied serum levels of inhibinA and inhibin pro-alpha-C at various stages of medical termina-tion of pregnancy using Mifepristone and Misoprostol.Mifepristone, a competitive inhibitor of progesterone receptors,is administered orally 48 hours before vaginal Misoprostol, a pros-taglandin analogue that induces uterine contraction and abortion.Mifepristone therefore exerts its clinical effect largely on thecorpus luteum while Misoprostol interrupts placental blood flowand causes expulsion of the fetoplacental unit. In this study, threegroups of patients undergoing medical TOP were sampled: thosepresenting below 7 weeks, at 7–8 weeks and 8–9 weeks of preg-nancy. Blood samples were collected immediately beforeadministration of Mifepristone, before administration ofMisoprostol and immediately on expulsion of fetus. Inhibin A andpro-alpha-C were assayed using a specific and sensitive enzyme-linked immunosorbent assays.

Results . We observed a significant fall in serum concentra-tion of inhibin pro-alpha-C following administration ofMifepristone, with a further reduction after administration ofMisoprostol. In contrast Mifepristone had no effect on serumlevels of inhibin A, which fell steeply only after administra-tion of Misoprostol.

Conclusion. The results suggest that interruption of corpusluteum with mifepristone results in a fall in production of pro-alpha-c while inhibin A, being a product of the fetoplacental unit,remains unaffected.

The effect of nitric oxide on trophoblastapoptosis

P. R. DASH,1 J. E. CARTWRIGHT,P. N. BAKER,2 A . P. JOHNSTONE1 andG. S. T. J. WHITLEY1St George’s Hospital Medical School, London and2School of Human Development, City Hospital,Nottingham, UK

Trophoblast invasion of the uterine wall is an essential step inestablishing and maintaining a normal pregnancy. Normaltrophoblast invasion requires stringent regulation of processes suchas cellular migration, cellular proliferation and apoptosis. It isthought that nitric oxide (NO) may have a role in many of theseprocesses. We have investigated the role of NO in trophoblastapoptosis using the trophoblast cell line SGHPL4. Apoptosis inthese cells was observed morphologically using time-lapsemicroscopy and was confirmed through the use of the caspaseinhibitor, Z-VAD. To investigate the role of NO in the regulationof apoptosis in trophoblasts, NO donors were added to the mediain increasing doses. The addition of DPTA-NONOate (half-life of3 hours) produced a delay in the onset of apoptosis, with the timetaken for 50% of cells to show signs of spermine-induced apoptosisincreasing from 3 hours to over 6 hours. The protective effect ofNO was even more pronounced when the NO donor PAPA-NONOate (half-life 15 minutes) was used. After 24 hours nearly90% of the cells treated with 10 _M spermine and 100 _M PAPA-NO were still healthy.

Hepatocyte growth factor (HGF) is able to increase NO pro-duction by stimulating iNOS. It was found that exposure to HGFsignificantly increased the survival times of cells exposed toapoptotic stimuli. The role of NO in this protection was con-firmed using the iNOS inhibitor 1400W to reverse theprotective effects of HGF. Further work will seek to demonstra tethe mechanism through which NO protects from apoptosis inthese cells.

In utero gene therapy by ultrasound-guidedpercutaneous administration of adenovirusvector into the muscle of fetal sheep

A. L. DAV ID, D. M. PEEBLES, M. THEMIS,1

T. COOK,2 C. COUTELLE1 and C. RODECKDepartment of Obstetrics and Gynaecology, Royal Freeand University College Medical School, UniversityCollege London; 1Cystic Fibrosis Gene Therapy ResearchGroup, Section of Molecular Genetics and 2Departmentof Histopathology, Imperial College School of Medicine,London, UK

Results of somatic gene therapy in adult patients are disappointing .In utero treatment may be more effective, by avoiding early onsettissue damage, immune-sensitisation and allowing targeting of organsystems which are less accessible in the adult.

We are developing the sheep fetus as a relevant animal modelto test percutaneous ultrasound guided methods of gene delivery. Wepresent results of a novel method of fetal gene delivery usingintramuscular injection.

Procedures were performed on fetuses of 50–61 days’ gestation(term 145 days) from ewes under general anaesthesia. A 22-gaugespinal needle (Becton Dickinson, Oxford, UK) was inserted underultrasound guidance into the fetal thigh where replication deficientadenoviral vectors containing the #gb#-galactosidase reporter gene(one sheep) or the human Factor IX gene (six sheep) were injected.A post mortem was performed at 48 hours, 9 days or 28 days; onesheep is going to birth.

Human factor IX levels in fetal plasma as determined by ELISA,were 1% at 48 hours, but did not increase further with increasingvirus dose or the use of DEAE-dextran polycation to enhance trans-duction. Nine days after injection, levels reached 15% of humanplasma concentration. Immunohistoche mistry for #gb#-galact osi-dase showed strong nuclear staining of injected muscle and overlying

J O

bste

t Gyn

aeco

l Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Uni

vers

itat d

e G

iron

a on

11/

21/1

4Fo

r pe

rson

al u

se o

nly.

Blair Bell Research Society 549

skin, with occasional staining in fetal liver and adrenal gland. Re-sults from PCR analysis of vector spread will be presented.

These data demonstrate that intramuscular gene transfer to thesheep fetus is feasible. Further investigation of the optimal timeand safety of this therapy is required.

Potential teratogenic effects of Benomyl

M. J. HEWITT,1 P. MUTCH,1

SIOBHAN M. QUENBY,2 P. N. BAKER2 andMARGARET K. PRATTEN1

1School of Biomedical Sciences and 2School of HumanDevelopment, University of Nottingham, UK

Background . A possible association between environmental expo-sure to Benomyl and anophthalmia has not been proven bypublished studies to date. The aim of the present study was to in-vestigate potential teratogenic effects of Benomyl using the ratembryo model. This model enables the culture of rat embryosfrom 9·5 to 11·5 days’ gestation in either rat or human serumwith similar growth and differentiation as would be expected invivo.

Methods . Explanted rat embryos were cultured in rat serum(n=121) or human serum (n=90) with differing concentrations ofBenomyl (170 nM–13·6 mM), dissolved in ethanol. In addition, 18embryos were cultured in both human and rat serum with theequivalent concentration of ethanol to act as a vehicle control. Thecultured embryos were then measured and scored for growth anddifferentiation by two blinded observers .

Result. Benomyl (>5 mM) produced a significant concentration-dependent deterioration in morphological score, somite numberand optic development. Gross toxic effects were noticed at con-centrations of (>12 mM) in rat serum and (>10 mM) in humanserum.

Conclusion . This study provides evidence that Benomyl is a poten-tial teratogen affecting many parameters, including optic development ,at levels below those that could be considered embryotoxic. Furthermore,optic development appeared to be exquisitely sensitive to the ef-fects of Benomyl at the higher concentrations.

Enhanced reactive oxygen species productionin Epstein– Barr virus immortalisedlymphoblasts from women who have had pre-eclamptic pregnancies: the role of priming

V IRGINIA M. LEE, A. W. F. HALLIGAN,A. I. PETTIT and L. L. NGDepartment of Medicine and Therapeutics andDepartment of Obstetrics and Gynaecology, LeicesterUniversity, UKObjective. To determine whether Epstein–Barr virus immortalisedlymphoblasts obtained from women who have had pre-eclampticpregnanci es show enhanced NADPH oxidase-mediated reactiveoxygen species (ROS) production in response to agonists.

Design. Cell lines were prepared from lymphocytes obtainedfrom women who had undergone either pre-eclamptic ornormotensive pregnancy. After immortalisation with Epstein–Barr

virus, ROS generation was measured following stimulation withphorbol myristate acetate (PMA).

Subjects . Lymphoblast cell lines from eight women who had apre-eclamptic pregnancy and eight age-matched women who hada normal pregnancy were included in the study.

Methods . A chemiluminescent technique was developed usingluminol to assess the production of ROS in immortalizedlymphoblasts after stimulation with PMA.

Results. The pre-eclamptic lymphoblast cell lines showedenhanced superoxide production compared to the control cell lines(1·948±0·30 vs. 0·754±0·18 arbitrary units, P=0·0060).

Conclusions . Our results suggest that Epstein–Barr virus immor-talised lymphoblasts developed from women who had previouspre-eclampsia show enhanced ROS production in response to PMA.This increased production may be due to priming of cells duringpre-eclamptic pregnancy or could represent an inherent predispo-sition to oxidative stress.

The effect of acute administration of 17 b-oestradiol on vessel tone ex-vivo

E. KIERAN,1 K. STEWART,2

SANDRA T. DAV IDGE,2 and P. N. BAKER1

1School of Human Development, City Hospital,Nottingham, UK and 2Department of Obstetrics andGynecology and Physiology, Perinatal Research Centre,University of Alberta, Edmonton, Canada

Introduction . There is a reduction in significant cardiovasculardisease of up to 50% with the administration of oestrogen duringand after the menopause. Alteration in lipid profile onlyaccounts for 50% of the beneficial effect on the vasculature.Oestrogen has a d irect effect on vascular tone. It remainsunclear as to whether this is endothelium-independent , orwhether the endothelium-derived relaxing factors, nitric oxide(NO), prostacyclin (PGI2) or endothelium-derivedhyperpolarising factor (EDHF) are involved. Acute oestrogenadministration can rapidly reduce vascular tone. This effectoccurs through a non-genomi c, rapid pathway.

Methods . Mesenteric resistance arteries were isolated fromSprague–Dawley rats 4 weeks following oophorectomy. Half ofthese animals (n=6) received oestrogen implants during surgery.The remaining animals (n=6) received placebo. Tone in vessel seg-ments was assessed using wire myography. Following phenylephrinepreconstriction, incremental concentrations of 17 b-oestradiol(10 -8–10 -5 M) were added in the presence of inhibitors:Meclofenamate 10 -5 M (cyclooxygenase inhibitor), L-NG-monomethyl-arginin e (L-NMMA) 250 mM (NO synthase inhibitor)and potassium chloride (KCL) 30 mM (EDHF inhibitor).

Results. Dose-dependent vasodilation occurred with 17 b-oestra-diol application. There was no significant overall effect from theendothelial inhibitors on oestrogen-induced relaxation. A tendencytowards reduced relaxation in the presence of L-NMMA was foundin the placebo group.

Conclusion . Oestradiol induces vasodilation in resistance arteriesin this model. Overall, inhibition of endothelium-derived vasodilatorsdid not affect vasorelaxation. However, there was a greater effectfrom NO synthase inhibition in the placebo group. This implicatesNO in endothelial-dependent relaxation induced by acute oestrogenapplication, but only in oestrogen-deprived animals.

J O

bste

t Gyn

aeco

l Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Uni

vers

itat d

e G

iron

a on

11/

21/1

4Fo

r pe

rson

al u

se o

nly.