Effects Of Several Methods On Contractility Of Isolated Uterine And Expression Of Uterine Contractile Related Protein In Rats During Late Pregnancy

Objective To explore the effects of salt load,alkali load,dexamethasone combined with oxytocin(OXT)on isolated uterine contractility and expression of uterine contraction-related protein in late pregnant rats,which would provide some theoretical basis for the clinical treatment of postpartum hemorrhage(PPH).Methods(一)salt load and alkali load42 pregnant 17-day SD rats were randomly divided into drinking tap water group(group A),2% Na Cl solution group(group B),5% Na HCO3 solution group(group C).Two rats were taken from each of the three groups at 0h,12 h,24h,36 h,48h,60 h and 72 h respectively,then were anesthetized,caesarean sectioned,taken arterial blood for blood gas analysis and uterine muscle strips for muscle tension measurement,finally the content of oxytocin receptor(OXTR)was measured by enzyme-linked immuno sorbent assay(ELISA).(二)dexamethasone combined with oxytocin6 pregnant 20-day SD rats were anesthetized and cesarean sectioned,4uterine muscle strips were taken equally from uterus of each rats,a total of 24 strips,then were randomly divided into blank control group(group D),oxytocin group(group E),dexamethasone group(group F),dexamethasone andoxytocin group(group G),after 30 minutes muscle tension of all strips were mesured respectively,then the m RNA and protein expression of OXTR,prostaglandin F2α receptor(PTGFR),urocortin1(UCN1)and connexin43(CX43)were detected by Real-time PCR,Western blot and ELISA respectively.Results(一)salt load and alkali load There were no significant differences in serum sodium ion and bicarbonate ion concentrations,muscle tension(including amplitude and frequency)and the content of OXTR among three groups at 0h(P>0.05).At other points in time,sodium ion concentration in group B and group C was significantly higher than that in group A(P<0.05),bicarbonate ion concentration in group C was higher than that in group A and group B(P<0.05).Muscle tension of group B were significantly higher than that of group A(except amplitude at 72h)(P<0.05),amplitude of group C was higher than that of group A at12 h,24h,60h(P<0.05),while frequency was higher than group A at 48 h,60h,72h(P<0.05).The content of OXTR in group B was significantly higher than that in group A(P<0.05),group C was higher than that in group A at12 h,24h,60 h,72h(P<0.05).(二)dexamethasone combined with oxytocin Comparing muscle tension among four groups,there were group G> group E> group D(P<0.05),group G> group F> group D(P<0.05),that is,dexamethasone combine with OXT is higher than that of OXT or dexamethasone alone,there was no significant difference between group E and group F(P>0.05).Comparing contractile related protein expression among four groups,OXTR,UCN1 and CX43 m RNA and protein in group G were higher than those in group E(P<0.05),UCN1 and CX43 m RNA and protein in group G were higher than those in group F(P<0.05),OXTR and CX43 m RNA and protein ingroup E and group F were higher than those in group D(P<0.05),there were no significant differences in PTGFR m RNA and protein expression among four groups(P>0.05).Conclusion(一)salt load and alkali load The salt load can increase uterine contractility and the level of OXTR,the same is true for 60 h of alkali load.(二)dexamethasone combined with oxytocin Dexamethasone combined with OXT has a stronger effect on contraction of uterine smooth muscle in late pregnant rats than that of OXT or dexamethasone,and the combination of dexamethasone and OXT can increase the m RNA and protein expression of OXTR,UCN1,and CX43 on uterine smooth muscle cells.