| Objective: Preeclampsia(PE) is a kind of hypertensi disorders of pregnancy, is a serious complication in obstetrics, poses a serious threat to the health of the mothers and fetus.Systemic small artery spasm is the basic pathological changes of preeclampsia-eclampsia. Use effective drugs to remove small artery spasm in the step-down at the same time improve systemic microcirculation and tissue ischemia hypoxia, could improve the conditions of the mother and the baby. At present Magnesium sulfate is widely applied to the antispasmodic drugs in clinical, but because of its treatment dose and toxic dose more close to the side effects and adverse reactions, no higher safety and effectiveness in the clinical application.. Traditional Chinese medicine preparation of tetramethylpyrazine(TMp) in cardiovascular disease has obvious curative effect to make clinical obstetrics workers begin to pay attention to, and used in the clinical treatment of pregnancy-induced hypertension syndrome, found that TMp(or joint Magnesium sulfate) in the treatment of pregnancy induced hypertension syndrome can effectively improve the patient’s clinical symptoms, reduce the occurrence of complications, with higher safety and effectiveness [1-6]. But the TMp mechanism in the treatment of pregnancy-induced hypertension is not clear. The study found that the normal human mesenteric artery smoothmuscle of big conductance Ca2+-activated channel(BKCa can be activated by TMp[7]. When BKCa is activated,the cell membrane super taking place, inhibit the activity of the voltage dependent calcium channel, reduce the internal flow of Ca2+, diastolic blood vessels, decline blood pressure [8]. BKCa as the ion channels in vascular smooth muscle is mainly responsible for regulating vascular smooth muscle tension. Mesenteric artery as the main blood vessels of forming peripheral resistance, is of important role to regulate blood pressure. Previous studie have confirmed that TMp have activated the BKCa channel in placenta small artery smooth muscle cells of patients with PE, and it have a certain concentration dependence of activation. This experiment adopts the single channel patch clamp technique to observe change of BKCa channels on PE patients mesenteric artery smooth muscle cells, and the changes of under the effect of TMp to the PE patients mesenteric artery smooth muscle cells BKCa changes, discusses the mechanism of action of TMp on PE and it have very important theoretical and practical significance to find more valuable drugs, can provide certain theoretical basis for the treatment of PE. Methods : â‘´Take the patients cesarean section surgery and were diagnosed of preeclampsia as PE group(15 cases);Take no obstetric complications and complications during this period, full-term birth of women because of scar uterus and pelvic factors cesarean delivery as normol late pregnancy( NLP) group(10 cases). We choosed the mesenteric arteries with the inner diameter about 1 ~ 2mm for this experiment,peeling perivascular adipose connective tissue gently, opening blood vessels longitudinally,cuting into small pieces of tissue about 2 mm × 2 mm.Application of two-step acute enzyme separation method to obtain a single smooth muscle cells. Chose stereo and slick vascular smooth muscle cells for experiment ⑵Adherent cells were placed in symmetric high potassium solution and in inside-out patch to observe the active changes of the two groups of mesenteric artery smooth muscle cells BKca. ⑶Under the condition of + 40 mv to polarization voltage, PE cell groups including 10 cases in low concentration(mmol/L) under the action of TMp(0.73, 2.20, 3.67, 2.20), the other 5 cases in relatively high concentrations(mmol/L) under the action of TMp(6.60, 8.07, 9.51), each within the cell-attached and inside-out patch clamp to record the current channel.â‘·Single channel current was amplified and filtered by patch clamp amplifier(CEZ-2200), then imported into the computer. Pclamp6.0 software was used to record and analyze. Results:â'ˆ In symmetrical high K+ solution, single channel currents on the human mesenteric artery smooth muscle cellswere recorded in inside-out patches. Single channel conductance was 227.11±12.365 p S(n=10). The channels were characterized by obvious voltage-dependent and calcium-dependent. In outside-out patch(Vm =+30 m V),the activation of BKCa could be blocked by 200 n M Ib TX completely.â'‰On inside-out patches with the concentration of Ca2+(10-7M) in bath solution(Vm =+40 m V),the NLP group has higher NPo,Amp and To,shorter Tc,compared with the PE group(n=10,P<0.05).â'ŠWith the concentration of Ca2+(10-7M) in bath solution(Vm =+40 m V), change the TMp concentration in the bath,(1) In PE group(low concentration of TMp group) cells:On cell-attached patch the BKca have no obvious change in NPo, Amp, tc and To(n = 10, P > 0.05); But on inside-out patch the BKCa have increased in NPo,shortened in Tc(n = 10, P < 0.05), reduced in To, no obvious change in Amp(n = 10, P > 0.05).(2) PE group(high concentration of TMp group) cells:On cell-attached patch the BKCa have no obvious change in NPo, Amp, Tc and To(n = 5, P > 0.05); But on inside-out patch when the concentration of the TMp tendency for 8.07 mmol / L, and increase the drug concentration the BKCa of NPo has not continued to increase, Tc does not continue to shorten, Amp, To no apparent change(n = 5, P > 0.05).Conclusions:1.The BKCa was inhibited in preeclampsia patients. 2.On the cell-attached patches, BKCa in mesenteric smooth muscle cells of PE patients’ was not obviously changed by TMp in different concentration. 3.On the inside-out patches, BKCa channels on PE patients’ mesenteric smooth muscle cells could be activated deirectly by tetramethylpyrazine within a certain concentration range andthis activation with certain concentration dependent manner.4.TMp in the extracellular and intervention to enter cell can reactive BKCa channel to has therapeutic effect on PE.5.The mechanism of associated preeclampsia for TMp may be related to BKCa channel activation of artery smooth muscle cell. |
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