The Change On The Large Conductance Calcium Activated Potassium Channels In Mesenteric Artery Smooth Muscle Cells During HDCP

Abstract:objective:Hypertensive disorders complicating pregnancy (HDCP) is a serious obstetric complication,,and is also the main reason for the raise of maternal and perinatal mortality. The classification of this diseases is complex,etiology and pathogenesis are not entirely clear.Many researchers believe that many factors coming from the interaction of maternal,fetal and placental due to the occurrence of HDCP. High blood pressure,one of the measurement standards,is the most outstanding clinical symptoms of the disease,one of the standard to measure the severity of disease.The ion channels on vascular smooth muscle cells are involved in the regulation of vascular tension,and the activation of large conductance calcium-activated potassium channels (BKca)-one type of the ion channels play an mportant role. When the BKca is continuous activation,cell membrane occur super.At the same time,voltage dependent calcium channel activity is restrained, and the internal flow of Ca2+is reduced.finaly,blood vessels are relax,and blood pressure begin to decline.BKCa plays a major role in maintain of resting membrane potential of vascular smooth muscle cells.Mesenteric artery, main visceral vessels of human beings, the largest proportion of vessels in body,is the main vessel of forming peripheral resistance,so has significant effects in regulating blood pressure. This experiment adopts patch clamp single channel recording technique,observation of the change of large conductance calcium activated potassium channels (BKca in mesenteric artery vascular smooth muscle cells with HDCP, explore the relationship between the pathogenesis with BKca in mesenteric artery smooth muscle cells with preeclampsia, provide theoretical basis for further study on the pathogenesis of this disease. Methods:We choosed the mesenteric arteries with the inner diameter about1-2mm for this experiment, peeling perivascular adipose connective tissue gently, opening blood vessels longitudinally,cuting into small pieces of tissue about2mm x2mm, and finally digesting in the two enzymes liquid in turn.The single smooth muscle cell observed at high magnification was with smooth And complete cell membrane,good cell refraction.We chose single channel patch-clamp techniques to recorde the currents.Single (CEZ-2200), and then imported into the computer. The pClamp10.1software was used to record data.The difference between HDCP group, NLP group,NP group in BKca currents was observed and compared.Results:1.Using two-step acute enzyme to isolate human mesenteric artery smooth muscle cells, we can obtain many of the single smooth muscle cells with high quality conforming to the experimental need.2. BKCa of human mesenteric artery smooth muscle cells isolated by two-step acute enzyme in this experiment has the following features:Large conductance; The channel has the voltage dependence and the calcium sensitivity.3. Compasion the activities of single BKCa current in mesenteric artery smooth muscle cells with the three groups:(1) The conductance value of HDCP group were lower than other groups, there were statistically significant (P<0.05).(2) In cell-attached patch, Current Amplitude(Am) in HDCP group was lower than in NLP group and NP group, there were statistically significant(P<0.05).this difference between NLP group and NP group were not obvious,there were no statistically significant(P>0.05).Open Probability (Po) in NLP group was largest in the three groups,and in HDCP group was least, namely PONLP组>PONP组>POHDCP组,there were statistically significant(P<0.05).Mean Open Time (To) in NLP group was longest in the three groups,and in HDCP group was shortest, namely TONLP组>TONP组>TOHDCP组,there were statistically significant(P<0.05).Mean Close Time (Tc) in HDCP group was longer than in NLP group and NP group,there were statistically significant(P<0.05).this difference between NLP group and NP group were not obvious,there were no statistically significant(P>0.05). In inside-out patch,Vm=+40mV,with calcium concentration increasing, the activities of single BKCa current in mesenteric artery smooth muscle cells with the three groups were different,there were statistically significant(P<0.05). Current Amplitude(Amp),Open Probability (Po),The mean Open Time(To) in HDCP group were lower than in NLP group,there were statistically significant (P<0.05).The mean Closed Time(To)in HDCP group were longer than in NLP group,there were statistically significant (P <0.05).Current Amplitude(Amp),Open Probability (Po),The mean Open Time(To) in HDCP group were lower than in NP group,there were statistically significant (P<0.05).The mean Closed Time(To)in HDCP group were longer than in NP group,there were statistically significant (P<0.05).these differences between NLP group and NP group were not obvious,there were no statistically significant(P>0.05).Conclusion:1.This experiment adopting the two-step acute enzyme to separate pregnancy mesenteric artery, can obtain enough smooth muscle cells with high quality, and is appropriate for patch clamp experiment.2. The pregnanct women mesenteric artery smooth muscle cells single channel current was recorded by this experiment is BKca,it has the characteristics of high conductivity, calcium dependence, voltage dependence.3.BKca in mesenteric smooth muscle cells of normal late pregnant women was activated, in order to maintain blood pressure balance and meet the needs of the pregnancy.4.BKca in mesenteric smooth muscle cells of HDCP was suppressed.Speculate that the change of the activity of BKca in mesenteric smooth muscle cells associated with HDCP.