动脉粥样硬化兔主动脉平滑肌细胞钙激活钾通道变化及其对钙敏感性的研究

[目的]探讨动脉粥样硬化(Atherosclerosis,AS)主动脉平滑肌细胞钙激活钾通道(Calcium-activatedPotas-siumChannel,KCa)变化及其对钙的敏感性。[方法]用酶消化法获取单个主动脉平滑肌细胞,通过膜片钳记录技术检测AS兔主动脉平滑肌细胞KCa通道的活性,并在浴液中分别加入不同浓度的Ca2+,以Pclamp7.0应用软件实时采样记录通道的开放概率(Po)、平均开放时间(To)、平均关闭时间(Tc)和电流幅值(Am),并以加钙前作对照观察上述参数的变化。[结果]AS组KCa通道的活性明显高于对照组;与加Ca2+前比较,对照组Po增加了(22.35±9.43)倍,而AS组仅增加了(5.31±0.42)倍(P<0.01)。[结论]AS兔血管平滑肌细胞KCa通道的活性明显增加,可能是AS血管发生代偿性扩张的机制之一;该通道对Ca2+的敏感性降低,可能是促进AS发展的因素之一。     

热损伤时下丘脑神经元延迟整流性K^＋通道的变化

目的：研究高温状态时下丘脑延迟整流钾通道特性的改变，探讨高温条件下出现热损伤的作用机制。方法：对急性分离的新生SD大鼠下丘脑细胞进行高温处理，采用细胞贴附式和内面向外式膜片钳记录方法，观察通道活动改变情况。结果：细胞经43℃处理40min后，K^ 通道活动阳性率下降到38％（n＝16），而对照组（37℃）为86％（n＝36，P＜0.05）;43℃高温处理60m in后，细胞K^ 通道活动阳性率下降到＜10％（n＝35），而对照组为78％（n＝78，P＜0.05），并且通道活动呈现多种形式。结论：高温可能通过对通道蛋白的破坏作用而改变通道活动特性。     

重度子痫前期子宫小动脉平滑肌细胞大电导钙激活钾通道的改变

目的研究重度子痫前期患者子宫小动脉平滑肌大电导钙激活钾通道的改变。方法选取2012年6月至2013年3月在泸州医学院附属医院产科住院分娩的20例患者的临床资料,其中临床诊断为重度子痫前期(severe preeclampsia,SPE)且无其它并发症和合并症进行剖宫产手术10例为SPE组;同期无产科并发症和合并症的足月孕产妇因其他原因行剖宫产手术终止妊娠者10例为正常晚孕(normal late pregnancy,NLP)组。取行剖宫产手术患者的子宫小动脉,采用急性酶分离法分离出小动脉平滑肌细胞,按平滑肌细胞的来源分为重度子痫前期组和正常足月妊娠组,采用单通道膜片钳技术记录子宫小动脉平滑肌细胞BKCa通道电流。结果妊娠期子宫小动脉平滑肌细胞BKCa通道单通道电流能被Ib TX通道特异阻断剂阻断,具有电压和钙离子浓度依赖性;在细胞贴附式膜片下,重度子痫前期组与正常足月妊娠组相比,BKCa通道开放概率减少(P0.01),电流幅值减小(P0.01)、平均开放时间减少(P0.01)、平均关闭时间无明显变化。结论重度子痫前期患者子宫小动脉平滑肌细胞BKCa通道活性降低。     

热损伤温度对新生SD大鼠下丘脑神经元膜上ATP激活单通道活动的影响

目的 观察下丘脑神经元热损伤温度（42℃）处理后ATP激活单通道的变化。方法 采用膜片钳技术的细胞贴附记录模式，记录通道的活动动力学。结果 发现经高温处理后，新生SD大鼠ATP激活单通道的长时程开放时间常数（τ02）、开放概率（P0）降低（P＜0．05），通道在膜上的数量和密度降低。结论 热损伤可以影响ATP激活单通道的活动。     

大电导钙激活钾通道β1亚基与子痫前期的相关性研究

目的：探讨胎盘组织和子宫平滑肌组织中大电导钙激活钾通道β1亚基（KCNMβ1）的表达,及其与子痫前期发病的关系。方法：轻、重度子痫前期组（研究组）和正常孕妇组（对照组）孕妇的胎盘组织及子宫平滑肌组织中KCNMβl mRNA的表达通过荧光定量PCR技术检测。采用ELISA法检测三组孕妇血清KCNMβl浓度变化水平。结果：各研究组中孕妇血清的KCNMβl水平、胎盘组织及子宫平滑肌中KCNMβl mRNA表达水平均明显低于对照组,差异均有统计学意义（P〈0.05）;而轻、重度子痫前期组比较差异均无统计学意义（P〉0.05）。结论：孕妇血清中KCNMβl表达降低,胎盘组织和子宫平滑肌中KCNMβl mRNA的表达降低与子痫前期的发病密切相关,可能参与了子痫前期的病理生理过程。     

热损伤时下丘脑神经元延迟整流性K~+通道活动的变化

目的 :研究高温状态时下丘脑延迟整流钾通道特性的改变 ,探讨高温条件下出现热损伤的作用机制。方法 :对急性分离的新生SD大鼠下丘脑细胞进行高温处理 ,采用细胞贴附式和内面向外式膜片钳记录方法 ,观察通道活动改变情况。结果 :细胞经 4 3℃处理 4 0min后 ,K+通道活动阳性率下降到 38% (n =16 ) ,而对照组 (37℃ )为 86 % (n =36 ,P <0 .0 5) ;4 3℃高温处理6 0min后 ,细胞K+通道活动阳性率下降到 <10 % (n =35) ,而对照组为 78% (n =18,P <0 .0 5) ,并且通道活动呈现多种形式。结论 :高温可能通过对通道蛋白的破坏作用而改变通道活动特性     

钙激活性中电导钾离子通道在人子宫颈癌组织中的表达及其在细胞增殖中的作用

目的:研究钙激活性中电导钾离子通道(IKCa1)在宫颈癌组织中的表达变化及其在宫颈癌HeLa细胞增殖中的作用。方法:应用RT-PCR技术检测18例正常宫颈组织及15例宫颈癌组织中IKCa1 mRNA的表达;利用IKCa1通道的阻断剂(克霉唑)处理宫颈癌HeLa细胞,MTT法观察细胞增殖的变化。结果:宫颈癌组织中IKCa1 mRNA的阳性表达率及表达水平(分别为73.33%、1.14±0.45)明显高于正常宫颈组织(分别为11.11%、0.86±0.23),P<0.05。克霉唑以浓度和时间依赖的方式阻滞HeLa细胞增殖,抑制HeLa细胞的生长,降低IKCa1 mRNA的表达水平。结论:IKCa1的异常表达可能与宫颈癌的发生、发展密切相关,降低其表达可能抑制宫颈癌细胞的增殖和生长。     

铅抑制大鼠背根神经元外向延迟整流钾通道

目的观察铅对电压依赖性外向延迟整流钾通道的作用。方法运用膜片钳技术，在急性分离的成年大鼠背根神经节细胞（DRGs）上进行。结果记录到DRG神经元外向延迟整流K+电流（IK），并观察到铅对IK的明显影响，1.0、2.0、4.0、8.0μmol/LPb2+作用后，IK平均分别减少（8.6±0.8）％、（38.6±6.2）％、（63.0±5.1）％和（89.0±8.8）％。Pb2+作用起效甚快，在Pb2+充分作用后，以普通外液冲洗，IK可得到不同程度的恢复。结论铅在较高浓度可阻断成年大鼠背根神经元电压依赖性外向延迟整流钾通道，这种阻断作用是剂量依赖性的、可逆的。     

石英对大鼠背根神经元高电压激活钙电流影响的探讨

[目的]通过分析石英作用后大鼠背根神经元(DRG)高电压激活(HVA)钙电流的变化,探讨石英对钙离子通道结构和功能的影响.[方法]原代培养DRG,分0、5、15、45、135μg/mL5个石英浓度组进行体外染尘,运用全细胞膜片钳记录技术记录不同染尘时间DRG HVA钙电流,每组记录约6个DRG.[结果]135μg/mL剂量组石英作用于DRG后HVA钙电流密度峰值为(-95.9±38.8)pA/pF,大干对照组和低剂量组,差异有统计学意义(P ＜0.05).HVA钙电流从30%升至70%的速率明显快于对照组和其他染尘组,差异有统计学意义(P＜0.01),但达峰时间差异无统计学意义(P＞0.05);135 μg/mL剂量组钙电流平均失活速率明显快于对照组和其他染尘组,差异有统计学意义(P=0.000),电流从峰值到记录结束时的下降率高于对照组和其他染尘组,差异有统计学意义(P＜0.05).45、135 μg/mL组的DRG膜电导值分别为(1 420.0±655.6)pS/μm2和(2257.4±454.2)pS/μm2,均高于对照组和低剂量染尘组,差异有统计学意义(P＜0.05).石英可使DRGHVA钙电流稳态激活曲线V1/2向正值方向移动约6.0～6.5mV,大于对照组,差异有统计学意义(P＜0.05),移动的幅度与染尘浓度关系不明显(P＞0.05);斜率k变化不明显(P＞0.05).石英作用后DRG HVA电流-电压(I-V)曲线形状改变不明显,对DRG HVA钙电流时间依赖性也没有明显影响.[结论]石英作用后DRG HVA钙通道结构和功能发生变化,使钙电流显著增大,呈激活快、失活也快的特征;另外,石英可使HVA钙通道在高刺激电压状况下(-10mV左右)更容易被激活.     

妊娠期高血压疾病钾通道功能的改变

目的 探讨妊娠期高血压疾病患者血管平滑肌细胞膜上钾电流之变化,为其病因研究提供理论依据.方法 对15例妊娠期高血压疾病孕妇及5例正常孕妇的胎盘采用急性酶解分离制备单个胎盘血管平滑肌细胞;全细胞膜片钳技术记录胎盘血管平滑肌细胞膜上钾通道电流情况.结果 ①妊娠期高血压疾病各组的细胞静息膜电位均增大,与对照组相比,有显著性差异(P＜0.01);②胎盘血管平滑肌细胞膜电容在各组间无显著性差异(P＞0.05);③与对照组相比,妊娠期高血压疾病各组胎盘血管平滑肌细胞钾电流密度均减小,差异具有显著性意义(P＜0.001).结论 妊娠期高血压疾病胎盘动脉血管平滑肌细胞的静息膜电位增大,钾电流密度减小.推测妊娠期高血压疾病发生可能与钾通道功能改变有关.     

下丘脑神经元中游离Ca^2＋的电生理测定法

目的：采用膜片钳技术通过对SD鼠乳下丘脑神经元上Ca^2 激活K^ 通道（KCa)Ca^2 敏感性的研究测定其细胞内游离Ca^2 浓度（[Ca^2 ]i)。方法：首先应用内面向外式研究不同[Ca^2 ]i时KCa通道诉开放概率（P0）,作出量效曲线,再应用细胞贴附式求得生理状态下此通道的开放概论,从量效曲线上查出的细胞内游离Ca^2 浓度。结果：试验表明SD乳鼠下丘脑神经元上KCa通道的P0具有对[Ca^2 ]i的高度敏感性,求得下丘脑神经元内的[Ca^2 ]为0.1μmol/L。结论：实验结果说明此电生理法测定[Ca^2 ]i具有较高的可靠性和准确性。     

Short-Term Supplemental Dietary Potassium from Potato and Potassium Gluconate: Effect on Calcium Retention and Urinary pH in Pre-Hypertensive-to-Hypertensive Adults

Potassium supplementation has been associated with reduced urinary calcium (Ca) excretion and increased Ca balance. Dietary interventions assessing the impact of potassium on bone are lacking. In this secondary analysis of a study designed primarily to determine blood pressure effects, we assessed the effects of potassium intake from potato sources and a potassium supplement on urinary Ca, urine pH, and Ca balance. Thirty men (n = 15) and women (n = 15) with a mean ± SD age and BMI of 48.2 ± 15 years and 31.4 ± 6.1 kg/m², respectively, were enrolled in a cross-over, randomized control feeding trial. Participants were assigned to a random order of four 16-day dietary potassium interventions including a basal diet (control) of 2300 mg/day (~60 mmol/day) of potassium, and three phases of an additional 1000 mg/day (3300 mg/day(~85 mmol/day) total) of potassium in the form of potatoes (baked, boiled, or pan-heated), French fries (FF), or a potassium (K)-gluconate supplement. Calcium intake for all diets was approximately 700–800 mg/day. Using a mixed model ANOVA there was a significantly lower urinary Ca excretion in the K-gluconate phase (96 ± 10 mg/day) compared to the control (115 ± 10 mg/day; p = 0.027) and potato (114 ± 10 mg/day; p = 0.033). In addition, there was a significant difference in urinary pH between the supplement and control phases (6.54 ± 0.16 vs. 6.08 ± 0.18; p = 0.0036). There were no significant differences in Ca retention. An increased potassium intake via K-gluconate supplementation may favorably influence urinary Ca excretion and urine pH. This trial was registered at ClinicalTrials.gov as {"type":"clinical-trial","attrs":{"text":"NCT02697708","term_id":"NCT02697708"}}NCT02697708.     

Calciuric Effects of Short-Term Dietary Loading of Protein,Sodium Chloride and Potassium Citrate in Prepubescent Girls

Objective: Studies using adult human subjects indicate that dietary protein and sodium chloride have negative effects on the retention of calcium by increasing urinary calcium excretion, while alkaline potassium improves calcium retention along with decreasing urinary calcium losses. This study investigated the effect of these dietary factors on acute urinary calcium excretion in 14 prepubescent girls age 6.7 to 10.0 years.

Methods: Subjects provided a fasting urine sample then consumed a meal containing one of five treatments: moderate protein (MP) providing 11.8 g protein, moderate protein plus 26 mmol sodium chloride (MP+Na), high protein (HP) providing 28.8 g protein, high protein plus 26 mmol sodium chloride (HP+Na), or high protein plus 32 mmol potassium as tripotassium citrate (HP+K). Urine was collected at 1.5 and 3.0 hours after the meal. Supplemental protein was given as 80:20 casein:lactalbumin. Test meals were isocaloric, and unless intentionally altered, components of interest except phosphate were equal between treatments. Each subject completed all five treatments.

Results: Urinary calcium excretion rose after the meal, peaking at 1.5 hours. There were no significant differences in calcium excretion between treatments at any time point. The high protein treatments did not result in a significant increase in either net acid or sulfate excretion at 1.5 hours compared to moderate protein. Dietary sodium chloride had no effect on urinary sodium or calcium excretion over the 3 hours. After the potassium treatment, sodium excretion increased (p≤0.002) and net acid excretion decreased (p<0.001) compared to other treatments at 1.5 hours.

Conclusions: In children, a simultaneous increase in protein and phosphorus due to increased milk protein intake did not increase acute urinary calcium excretion. An effect of dietary sodium chloride on acute urinary calcium excretion was not observed. Both these findings were similar to those of adult studies previously conducted in the same laboratory using similar format and treatments. Potassium citrate was not hypocalciuric in children, a response differing from that for adults, who have shown a decrease in acute urinary calcium excretion in response to alkaline potassium treatment. Further characterization of calciuric responses to dietary factors is required for children, who may differ from adults in many respects.     

低温对家兔振动性神经功能的损伤

[目的]探讨家兔低温敏感性与振动性神经功能损伤之间的相关性。[方法]首先对家兔进行低温试验,按照试验前后测定指标的变化情况,确定内皮素（ET）、感觉神经传导速率（SCV）为低温敏感性指标。根据低温试验前后ET、SCV的变化情况分别进行分组。前后变化〈25％者为低度敏感组;变化25％～50％者为中度敏感组;变化〉50％者为高度敏感组。分组后,低、中、高度敏感组家兔分别为15、13、12只。然后,进行接振试验,测定各组家兔接振后SCV、感觉神经动作电位波幅、感觉神经动作电位潜伏时、运动神经传导速率（MCV）、运动神经远端波幅、运动神经远端潜伏时的变化。[结果]与接振试验前比较,接振后SCV、MCV、感觉神经动作电位波幅、运动神经远端波幅降低,感觉神经动作电位潜伏时、运动神经远端潜伏时延长（P〈0．05）。SCV、MCV、感觉神经动作电位波幅、运动神经远端波幅在低、中、高敏感组依次降低;感觉神经动作电位潜伏时、运动神经远端潜伏时依次延长,差异有统计学意义（P〈0．01）。将低温试验后的血浆ET浓度、SCV测定值与接振后的振动性神经功能损伤指标SCV（r=-0．872,r=0．847）、感觉神经动作电位波幅（r=-0．750,r=-0．925）、感觉神经动作电位潜伏时（r=0．850,r=-0．799）、MCV（r=-0．705,r=0．843）、运动神经远端波幅（r=-0．943,r=0．940）、运动神经远端潜伏时（r=0．941,r=-0．931）的测定值进行简单相关分析,结果显示上述相关系数r值均具有统计学意义（P〈0．01）。[结论]低温敏感性与振动性神经功能损伤具有相关性;振动性神经功能损伤在低、中、高3个敏感组中依次加重;但两者相关性的原因尚待研究。     

Global Trends (1961–2017) in Human Dietary Potassium Supplies

Background: Potassium (K) is an essential mineral and major intracellular electrolyte involved in the regulation of blood pressure, muscle contraction and nerve transmission in humans. Major dietary sources of K include fruits and vegetables, starchy roots and tubers, and whole grains. The aim of this study was to assess and report: (i) the sufficiency of K in national food systems globally, (ii) to quantify the contribution from food groups, and (iii) to explore spatial and temporal trends in the period of 1961–2017. Methods: Food supply and demography (1961–2017), K composition and K requirement data were combined to estimate per capita human dietary supplies of potassium (DSK), adequate intake of K (AIK) and K sufficiency ratio (KSR) at national, regional, continental and global levels. Results and Discussion: Globally, the mean ± SD. DSK (mg capita⁻¹ d⁻¹) increased from 2984 ± 915 in 1961 to 3796 ± 1161 in 2017. There was a wide range in DSK between geographical regions and across years, with particularly large increases in east Asia, where DSK increased from <3000 to >5000 mg capita⁻¹ day⁻¹. Roots and tubers contributed the largest dietary source of K, providing up to 80% of DSK in most regions. At the global level, throughout the 57-year period, the population-weighted KSR was <1 based on the 2006 Institute of Medicine AIK recommendation, while it was >1 based on the 2019 National Academies of Science and the 2016 European Union AIK recommendation. While KSR ≥ 1 shows sufficiency of DSK, KSR < 1 does not indicate K deficiency risk. Conclusion: Due to the absence of a Recommended Daily Allowance (RDA) for K, this study used the ratio of DSK:AIK (i.e., KSR) to assess dietary K sufficiency. Estimates of dietary K sufficiency are, therefore, highly sensitive to the AIK reference value used and this varied greatly based on different institutions and years. To quantify the risk of dietary K deficiency, bridging the data gap to establish an RDA for K should be a global research priority.     

镰刀菌毒素脱氧雪腐镰刀菌烯醇对心肌细胞Ca2+通道的阻滞作用

目的观察镰刀菌毒素单端孢霉烯族化合物脱氧雪腐镰刀菌烯醇(DON)对培养心肌细胞Ca2 通道单通道电活动的影响.方法取新生1～2日龄Wistar大鼠,分离心肌细胞,培养基为80%DMEM与20%小牛血清,于37℃,在含5%CO2与95%空气的培养箱内进行培养,于培养24～48h期间进行实验记录.采用贴附式膜片钳技术,记录心肌细胞B、L、T三型Ca2 通道单通道电活动为加入毒素前对照,然后向培养基中加入1 mg·ml-1DON,以观察DON对心肌细胞Ca2 通道单通道电活动的影响.结果DON浓度为1 mg·ml-1时,心肌细胞B,L,T三型Ca2 通道均受到明显的阻滞.其阻滞作用表现在使B、L、T三型Ca2 通道的开放时间分别缩短47.3%,42.1%和17.1%,关闭时间分别延长283.3%,92.8%和40.7%,使通道的开放概率分别下降77.8%,71.1%和42.8%.而对流过B,L,T三型Ca2 通道的Ba2 流幅值均无明显影响.结论DON能抑制大鼠培养心肌细胞的Ca2 通道.     

Randomized Trial on the Effects of Dietary Potassium on Blood Pressure and Serum Potassium Levels in Adults with Chronic Kidney Disease

In the general population, an increased potassium (K) intake lowers blood pressure (BP). The effects of K have not been well-studied in individuals with chronic kidney disease (CKD). This randomized feeding trial with a 2-period crossover design compared the effects of diets containing 100 and 40 mmol K/day on BP in 29 adults with stage 3 CKD and treated or untreated systolic BP (SBP) 120–159 mmHg and diastolic BP (DBP) <100 mmHg. The primary outcome was 24 h ambulatory systolic BP. The higher-versus lower-K diet had no significant effect on 24 h SBP (−2.12 mm Hg; p = 0.16) and DBP (−0.70 mm Hg; p = 0.44). Corresponding differences in clinic BP were −4.21 mm Hg for SBP (p = 0.054) and −0.08 mm Hg for DBP (p = 0.94). On the higher-K diet, mean serum K increased by 0.21 mmol/L (p = 0.003) compared to the lower-K diet; two participants had confirmed hyperkalemia (serum K ≥ 5.5 mmol/L). In conclusion, a higher dietary intake of K did not lower 24 h SBP, while clinic SBP reduction was of borderline statistical significance. Additional trials are warranted to understand the health effects of increased K intake in individuals with CKD.     

经口摄入硫酸铝钾对兔肝肾影响的实验研究

目的：为探讨铝对家兔肝肾的影响。方法：将兔给予不同剂量的硫酸铝钾8周，测定肝、肾组织中铝、铜，锌、锰的含量及SOD，GSH－Px活力，同时做病理检查。结果：随着硫酸铝钾摄入量的增加，肝肾组织中铝水平升高（P＜0．001），而铜，锌，锰水平有不同程度的下降（P＜0．05，P＜0．01），SOD活力在高剂量组有显性降低（P＜0．05，P＜0．01），而GSH－Px的活力在低，高剂量组均有显性下降（P＜0．05，P＜0．01），对组织切片光镜下观察，低，高剂量组的肝、肾组织均有损伤，特别是高剂量组损伤严重。结论：铝通过拮抗其它微量元素而抑制SOD，GSH－Px的活性是造成肝，肾损伤的机理之一。