$216

492

SMFM Abstracts

REDUCTIONS IN THE ALPHA 3 ISOFORM OF THE SODIUM PUMP IN TERM PLACENTA MAY INDUCE HORMONAL SECRETION THAT MEDI- ATES ACTIVE LABOR STEVEN GRAVES], MICHAEL ESPLIN 2, BARDETT FAUSETT 2, DAVID FAUX1; 1Brigham Young University, Chemistry and Biochemistry, Provo, UT; 2Unive~ity of Utah, Obstetrics and Gynecology, SLC, UT

OBJECTIVE: The sodium pump (SP), occurring as three isoforms, regulates cell Na and K. Reduction of SP activity can result in the secretion of selected cytokines, prostanoids and steroid hormones, some of which are known to be secreted by the anmiochorion or placenta as part of labor. We hypothesized that reductions in one or more SP isolorms would accompany active labor and as such might contribute to membrane or placental secretions that initiate and /o r maintain labm:

STUDY DESIGN: Samples of placenta and amniochorion were obtained front vaginal deliveries of women in spontaneous labor. Non-laboring specimens were acquired at Caesarean section front women of comparable gestational age. Tissues were homogenized, separated by PAGE, and probed with specific monoclonal antibodies. Membranes were scanned to determine the relative protein abundance. An unpaired Student's t test was used to compare each isoform's abundance between the laboring and non-laboring groups by tissue. A Pvalue <.05 was considered significant.

RESULTS: Women in both groups were of comparable gestational age (GAl. There was no apparent change in abundance of any SP isoform with GA for either group. There were no differences between any SP isoiorm in amniochorion between laboring (112) and non-laboring (23) women. In contrast placental levels of all three SP alpha isoforms increased with GA until 39-40 weeks. The alpha i isoform showed a significant decrease thereafter. Placental levels of alpha 1 and 2 were not different for laboring and non- laboring women. However, women who experienced spontaneous labor had markedly lower alpha 3 isoform levels than those who had not (Labor: 46.9 + 3.7; Non-labor: 91.2 + 27.6 density units, P = .002).

CONCLUSION: As a consequence of the reduction of placental alpha 3 isoform, placental secretion of regulatory factors or hormones, important in the initiation and maintenance of labor, may be increased.

494

December 2001 AmJ Obstet Gynecol

CARBETOCIN IM INJECTION VS OXYTOCIN IV INFUSION FOR PRE- VENTION OF POSTPARTUM HEMORRHAGE IN WOMEN AT RISK FOL- LOWING VAGINAL DELIVERY MARC BOUCHER 1, CARL NIMROD 2, GEORGES TAWAGI2; 1Ste-Justine Hospital, U. of Montreal, Montreal, QC: 2The Ottawa Hospital, U. of Ottawa, Ottawa, ON

OBJECTIVE: To compare the efficacy of a single 100~tg im carbetocin (CBT) injection, a long-acting oxytocin (OT) agonist, to a 2h 10U OT iv infusion in reducing the incidence and severity of postpartum hemorrhage (PPH) in women at risk.

STUDY DESIGN: 154 wornen took part in this randomized double-blind double-dmmny study. 80 received 100~g CBT im and iv placebo after placental delivery.• 74 received placebo im and OT iv infilsion. CBC was done at entry and 24h postpartum. Among outcome measures were the need for additional tuerotonic agent, uterine massage, hemoglobin/hematocri t drop and blood loss.

RESULTS: Exploratory evaluation of the raw data reveals that the population was similar for each group regarding maternal age, parity, and gestational ageas well as for risk factors for PPH. Outcome measures appear in the following Table.

CONCLUSION: Patients receiving a single 100~tg im CBT injection required significantly less uterotonic intervention compared to patients receiving a continuous 2h iv OT infusion. It suggests that a single im CBT injection can advantageously prevent PPH in women at risk when compared to a continuous OT iv infusion.

Table

CARBETOCIN O X Y T O C I N P N = 80 N = 74 VALUE

Additional uterotonic agent 12 (15%) 12 (16.2%) >.05 Uterine massage 35 (43.8%) 47(63.5%) <.02 Uterotonic agent or massage 36 (45%) 48(64.9%) <.02 Hemoglobin drop (g/L) 12.8 +_ 11 16.3 +_ 11.7 >.05 Hematocrit drop 0.037 + 0.03 0.047 + 0.04 >.05 % of Hb drop from initial value 10.5 + 9.4 13.2 + 9.5 >.05 Blood loss estimate (mL) 412.9 _+ 198 415.6 + 194 >.05

493 AN IN-VITRO MODEL ASSESSING MATRIX METALLOPROTEINASE AC- TIVITY IN THE LATE GESTATION FETAL-MATERNAL INTERFACE ULUN ULUG t, AMIR WEISS 1, SHLOMIT GOLDMAN 1, IZHAR BEN- SHLOMO 1, ELIEZER SHALEV2; IHa 'Emek Medical Center, Obstetrics and Gynecology', Afula; 2Techuion-Israel Institute of Technology, Rappaport Faculty of Medicine, Haifa

OBJECTIVE: To establish an in vitro model for the study of matrix metalloproteinases (MMPs) activity, and their inhibitors (TIMPs) in the tissues of the fetal-maternal interface: decidua, chorion and amnion; and to use it for the assessment of drugs which delay or enhance labor.

STUDY DESIGN: Tissues were obtained at elective C/S from 7 term, non- laboring women. Decidua was taken from the lower uterine segment, away from the implantation site. Amnion and ehorion were separated from the chorionic plate. Samples were incubated in minimal media containing PGF2c( as follows: 0 (control), 0.1, 1.0, and 10 pg/ml. Incubations were also done with indomethacin as follows: 10-4, 10-5, 10-6M. MMP activity was measured in the incubation media using gelatin substrate-zymography. Conditioned medium TIMP-I levels were measured using western blot analysis.

RESULTS: Decidua had more MMP-2, MMP-9 and TIMP-1 then the membranes. In the decidua, PGF2c~ caused a 2.4 and 1.9-fold increase in MMP- 2 and MMP-9 activity respectively, and an 11.3-fold increase in the active form of MMP-2. PGF20~ brought about a 70% decrease in TIMP-1 levels. PGF2~ did not have an affect on the membranes, in chorion, iudomethacin brought about a 78 % and 35% decrease of MMP-2 and MMP-9 production, respectively: and in amnion 70% and 58% decrease,. Indomethacin caused a 4.1 fold increase of TIMP-I in the chorion and a 4.5 fold increase of TIMP-1 in the amnion. Indomethacin had no significant effect on the decidua.

CONCLUSION: Baseline levels of MMP-2, MMP-9 and TIMP-1 were higher in the decidua than in the membranes. PGF2~ caused a further increase while the membranes remained quiescent to this labor-inducing drug. Paradoxically, only the fetal membranes responded to indomethacin, decreasing MMP activity and increasing TIMP levels. This model can be applied to other substances, enriching our understanding of the dynamics between these tissues and their role in labor propagation and preterm labor prevention.

495 THE INTENSITY OF UTERINE CONTRACTIONS IN RATS DURING PREGNANCY AND PARTURITION CAN BE ESTIMATED FROM ELEC- TROMYOGRAPHY SIGNALS SHAO-QING SH1 l, WILLIAM MANER ], HOL- GER MAUL 1 , GEORGE SAADE t, ROBERT GARFIELD l, 1University of Texas Medical Branch, Obstetrics and Gynecology, Galveston, TX

OBJECTIVE: The purpose of this study was to determine if the intensity of uterine contractions as measured by intrauterine pressure (IUP) recordings, correlates with the energy of uterine electrical bursts obtained by electro- myography (EMG) in pregnant rats.

STUDY DESIGN: Four timed-pregnant Sprague-Dawley rats on day 14 (term = 22 days) were outfitted with internal telemetry devices to simulta- neously measure uterine EMG and IUP through bi-polar electrodes sutured to the uterine wall and a catheter inserted into the same uterine horn, respectively. Uterine EMG and IUP were recorded continuously in the conscious, unrestrained animals from dl6 of gestation until postpartum at a sampling rate of 10 Hz (band-pass filtered from 0.3 to 5 Hz). Data were transmitted to a recording system (MacLab 16/s, AD Instruments, Castle Hill, Australia) using an external receiver (RLA 1020 telemetry receivers, Data Sciences). The energy of eleeu-ical but~ts was analyzed by calculating the area under the power density spectrum (AUPDS) front 0.625 to 5.000 Hz. using Chart software (AD Instrmnents). For each time-point, the magnitude, duration and integral of corresponding uterine conn'actions were calculated. Spearman's Rank Order correlation was used to compare EMG and IUP parameters (significance: P< .05).

RESULTS: Between days 16 and 21, the AUPDS and the IUP parameters increased slightly. On d21 significant increases in both the uterine electrical energy (AUPDS) and the IUP parameters were observed. These increases peaked at the time of parturition on d22 and decreased after delivery. All 1UP parameters were highly correlated with the AUPDS (Table).

CONCLUSION: Electrical and mechanical energy of uterine contractions during pregnancy and parturition in conscious, unrestt~ained rats are highly correlated. Uterine EMG recording can be used to deternrine the force of uterine contractions.

Table Correlation of AUPDS with integral, duration and magmmde

INTEGRAL D U R A T I O N M A G N I T U D E

R P R P R P VALUE VALUE VALUE VALUE VALUE VALUE

AUPDS 0.718 <.01 0.841 <.001 0.890 <.001 Integral 0.902 <.001 0.768 <.01 Duration 0.802 <.001