| Objective: Magnesium sulfate is commonly used inpreeclampsia patients (preeclampsia, PE)，but it’s effective treatmentconcentration is close to the concentration of poisoning. To monitor thepatients’ basic situation increases the pressure of work. Large doses ofmagnesium sulfate inhibits contractions, affects labor progress, increasespostpartum blood loss, also has certain influence to the newborn.Tetramethylpyrazine(TMp) which is widely applied in the field ofcardiovascular diseases such as hypertension, coronary heart disease,arteriosclerosis, can anti platelet aggregation (the same work toaggregated platelet), dilate arteries, reduce vascular resistance, improvethe microcirculation, invigorate the circulation of blood. TMp (or togetherwith magnesium sulfate) treatment can effectively improve the patient’smicrocirculation, lead vasodilation increaseing the blood supply ofimportant organs, reduce the occurrence of complications, as well as fewadverse outcomes[16]. Big conductance Ca2+-activated channel(BKca)distributed in most of the smooth muscle cells is the most important typeof potassium channels,and is associated with the rectifying.The activity ofthe channel can be changed by the cells environment, as the activity reducced (or even the deactivation),the membrane showed obviousdepolarization or long potential cycle, Cause long exciting time andhigher the organization tension[7]. So BKca is relevanted to regulatingblood vessel tone of drugs. Our experiment investigate the changes ofBKca in patients placental chorionic plate resistance arteries smoothmuscle cells(CPASMCs), and the relationship between TMp and BKca.Elucidating the treatment mechanism to explore the pathogenesis ofhypertensive disorder complicating pregnancy and improve the treatmentmethod. Methods:⑴15patients with preeclampsia set as the casegroup(PE group). Similar gestational termination of normal latepregnance women(15patients) as the control group(NLP group). As soonas the patient parturition Through vaginal delivery or Cesarean delivery,placental chorionic plate resistance arteries was removed and dissectedfree of surrounding tissue under microscopic guidance, single vascularsmooth muscle cells were obtained after acute enzymatic hydrolysis.⑵All patch clamp experiments were performed on single smooth musclecells in symmetric high potassium solution ([K+]+0:[K]i=140:140mM).Observe the changes between PE group and NLP group ininside-out patches.⑶Ionic currents of PE group were recorded usingsingle channel cell-attached and inside-out patch clamp recordingtechnique at+40mV holding potential in exposure of differentconcentrations of TMp(0.73,2.20,3.67,5.14mmol/L).⑷Single channel current was amplified and filtered by patch clamp amplifier(CEZ-2200),then imported into the computer. Pclamp6.0software was used to recordand analyze. Results:⒈In symmetrical high K+solution, single channelcurrents on the CPASMCs were recorded in inside-out patches. Singlechannel conductance was217.26±10.84pS(n=15). The channels werecharacterized by obvious voltage-dependent and calcium-dependent.200nM Iberiotoxin（IbTx）could block the activities of channels almostcompletely.⒉On inside-out patches with the concentration of Ca2+(10-7M)in bath solution，the NLP group has higher NPo,Amp and To，shorterTc,compared with the PE group (n=15，P<0.05).⒊On cell-attachedpatches with the concentration of Ca2+(10-7M) in bath solution，eachconcentration of the TMp didn’t have any effect on BKca channels, i.e. nochanges in NPo, Amp, To and Tc could be found. While Oncell-attached patches it was completly different. TMp aetivated BKcachannels by invreasing NPo and Po, decreasing Tc, but Amp was notobviously changed. Conclusions:⑴The BKca was inhibited inpreeclampsia patients.⑵On the cell-attached patches, BKca channels onPE patients’ CPASMCs was not obviously changed by TMp in differentconcentration.⑶On the inside-out patches, BKca channels on PEpatients’ CPASMCs could be activated deirectly by tetramethylpyrazinein a concentration dependent manner.⑷The mechanism of associatedpreeclampsia for TMp may be related to BKca channel activation of artery smooth muscle cell. |
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