正常人血小板介电谱的实验研究

在100KHz～110MHz范围内,测量人血小板的介电谱,分析了人血小板对交流电场的介电响应的数据特征。利用频域阻抗技术首次测量了正常人血小板交流阻抗,绘制血小板的介电常数和电导率与电场频率的关系曲线。建立了人血小板的介电谱和Cole-Cole图,明确了人血小板的介电频响的数据特征。在射频电场中,人血小板的介电常数和电导率具有频率依赖性,血小板介电谱具有两个特征频率:第一特征频率fC1为6.66MHz,第二特征频率fC2为9.81MHz。     

骨骼肌细胞的介电弛豫特性

在100Hz～100MHz频率范围内,利用非线性数值计算和曲线拟合分析,验证了蛙离体骨骼肌细胞的介电弛豫特性满足Cole-Cole公式(误差≤3.45%),通过频域介电谱、Cole-Cole图、介电损耗因子和介电损耗角正切频率谱的曲线拟合分析,确定了蛙骨骼肌细胞的Cole-Cole介电参数:高频段相对介电常数εh=78,第一相对介电增量△ε1=113000,第二相对介电增量△ε2=45000,第一特征频率fc1=9 kHz,第二特征频率fc2=158 kHz,第一相位角β1=0.881,第二相位角β2=0.984,低频段电导率κL=0.55mS/cm,常数A=35,常数m=1.08.     

人血液介电谱Cole-Cole数学模型的解析

通过Cole-Cole方程的数值计算,对人血液介电谱实验数据进行曲线拟合的残差分析,建立人血液Cole-Cole数学模型参数。在104～108 Hz频率范围,使用Agilent 4294A阻抗分析仪测量30人70例全血导纳,并利用Cole-Cole方程的非线性数值计算,对实测数据进行曲线拟合,计算曲线拟合的残差数值。人血液介电谱的Cole-Cole数学模型参数:高频极限介电常数εh=45±5;第一弛豫介电增量Δε1=6 200±350、第一特征频率fC1=(500±5)kHz、第一弛豫分布系数β1=0.86±0.06、第二弛豫介电增量Δε2=990±310、第二特征频率fC2=(2.7±0.1)MHz、第二弛豫分布系数β2=0.975±0.015、低频极限电导率κl=(4.15±0.85)mS/cm。人血液细胞介电行为可以通过介电频谱、Cole-Cole图、介电损耗因子频谱、电导率虚部频谱及损耗角正切频谱等5个频谱进行表征,建立Cole-Cole模型参数。     

人肝癌细胞电阻抗特性的实验研究

在0.01~100MHz频率内,使用Agilent 4294A阻抗分析仪测量了人肝癌SMMC-7721细胞的交流阻抗,通过电阻抗谱、Bode图、Nyquist图和Nichols图观察了细胞体积分数(CVF)对肝癌细胞电阻抗特性的影响。结果表明:1频率依赖性:电阻抗实部增量、虚部增量(ΔZ′、ΔZ″)、幅模增量(Δ|Z*|)和相位角增量(Δθ)皆随频率发生变化;2CVF依赖性:当CVF增加时,低频极限增量值(ΔZ′0、Δ|Z*|0)、峰值(ΔZ″p、Δθp)、曲线面积和半径(Nyquist图、Nichols图)均随之增大;3存在两个特征频率:第一特征频率(fC1)和第二特征频率(fC2),分别来源于细胞膜与细胞外液、细胞质交界面的极化作用。结论:电阻抗谱方法能够观察人肝癌细胞电特性,可用于探讨肝癌细胞电生理机制变化,为进一步筛选抗肿瘤药物提供研究手段和观测指标,具有重要的理论价值和潜在的应用前景。     

频域阻抗法研究细胞介电特性

对生物细胞介电特性的研究是生物医学物理学公认的前沿重点课题之一.本文介绍如何采用宽频域交流阻抗技术研究细胞介电特性的原理和方法,以及在细胞介电谱的基础上,如何通过非线性数值计算建立细胞的数学模型和物理模型.本文以蛙骨骼肌细胞为例,在100Hz～100 MHz范围内,应用阻抗分析仪测量了细胞交流阻抗,通过细胞介电谱、Cole-Cole图、介电耗损因子频率谱、介电损耗角正切频率谱等方式,分析了骨骼肌细胞介电特性的数据特征;最后使用Cole-Cole模型和椭圆壳介电理论,建立了骨骼肌细胞的数学模型和物理模型,为今后利用数理模型方法分析骨骼肌疲劳、骨骼肌萎缩等奠定了基础.     

正常人血小板射频段介电响应测量

目的在射频段测量正常人血小板介电谱,建立血小板对交流电场介电响应的数据特征。方法利用频域阻抗技术测量人血小板交流阻抗,经过介电谱、Cole-Cole图、介电损耗因子Δε”、导电率虚部Δκ”、介电损耗角正切Δtgδ等频谱,明确人血小板介电频响的数据特征。结果在射频电场中,人血小板的介电常数和电导率具有频率依赖性;血小板介电响应具有两个中心特征频率:第一中心特征频率fC1=6.66MHz,第二中心特征频率fC2=9.81MHz。结论交流阻抗技术能够测量血小板射频段介电响应。     

正常人血小板射频段介电响应测量

目的 在射频段测量正常人血小板介电谱,建立血小板对交流电场介电响应的数据特征.方法 利用频域阻抗技术测量人血小板交流阻抗,经过介电谱、Cole-Cole图、介电损耗因子△ε"、导电率虚部△κ"、介电损耗角正切△tgδ等频谱,明确人血小板介电频响的数据特征.结果 在射频电场中,人血小板的介电常数和电导率具有频率依赖性;血小板介电响应具有两个中心特征频率:第一中心特征频率fC1=6.66 MHz,第二中心特征频率fC2=9.81 MHz.结论 交流阻抗技术能够测量血小板射频段介电响应.     

垂直和平行方向的骨骼肌介电谱的比较研究

在10Hz-100MHz频率范围内，应用阻抗分析仪测量了骨骼肌纤维走行与测量电场呈垂直和平行两个方向上的蛙离体骨骼肌的介电谱。比较了平行和垂直于外施电场方向的骨骼肌细胞介电谱的区别：（1）在低频低，平行方向电导率（K1，∥）高于垂直方向电导率（K1，⊥）近10倍；（2）在高频段，平行方向电导率（Kh,∥）与垂直方向电导率（Kh,⊥）不相等，存在着约0.8mS/cm的差值；（3）在电导率Cole-Cole图上，平行方向电导率增量（△k∥)低于垂直方向电导率增量（△k⊥);(4)在介电损失（ε“)方面，平行方向介电损失（ε“∥）主峰明显高于垂直方向介电损失（ε“⊥)主峰；（5）在介电损耗角正切（tgδ）方面，平行介电损耗正切（tgδ∥）主峰的频率滞后于垂直方向介电损耗角正切（tgδ⊥）主峰的频率，但是tgδ∥峰值高于tgδ⊥峰值。     

大鼠腓肠肌细胞介电谱测量和Cole-Cole数学模型分析

测量大鼠腓肠肌细胞介电谱,利用Cole-Cole方程的曲线拟合建立Cole-Cole数学模型参数.在100 Hz～100 MHz频率范围,使用Agilent 4294A阻抗分析仪对电场与肌纤维方向呈平行和垂直的大鼠腓肠肌进行了阻抗测量,并利用Cole-Cole方程的数值计算,对细胞介电谱、Cole-Cole图、介电损耗因子频谱、电导率虚部频谱和损耗角正切频谱进行曲线拟合分析和残差分析,比较电场与肌纤维方向呈平行或垂直两种情况的介电行为区别.结果表明:骨骼肌细胞的介电弛豫具有两个特征频率,其平行方向的特征频率低于垂直方向;平行方向的介电增量高于垂直方向的介电增量;平行方向的低频极限量高于垂直方向的低频极限量;平行方向和垂直方向的介电常数高频极限量相等;平行方向和垂直方向的电导率高频极限量存在一定差距.平行方向的电导率虚部频谱和损耗角正切分别高于垂直方向的值,但是,平行方向的电导率虚部最大值低于其垂直方向的值.腓肠肌细胞的介电常数和电导率存在频率依存性和各向异性,其介电行为存在α和β两个介电散射,并满足Cole-Cole数学模型.     

人血液细胞介电谱的实验研究

在0．01～100MHz范围内，测量人血液细胞的介电谱，确立人血液细胞对交流电场的介电响应的数据特征。利用频域阻抗技术测量了正常人血液细胞交流阻抗，绘制细胞的介电常数和电导率与电场频率的关系曲线。建立了人血液细胞的介电谱和Cole—Cole图，明确了人血细胞的介电频响的数据特征。在射频电场中，人血液细胞的介电常数和电导率具有频率依赖性，表现为具有两个特征频率的介电弛豫：第一介电弛豫发生在fc。为1．42MHz，第二介电弛豫产生在fcz为3．32MHz。     

Trimetazidine reduces basal cytosolic Ca2+ concentration during hypoxia in single Xenopus skeletal myocytes

We tested the hypotheses that: (1) Ca(2+) handling and force production would be irreversibly altered in skeletal muscle during steady-state contractions when subjected to severe, prolonged hypoxia and subsequent reoxygenation; and (2) application of the cardio-protective drug trimetazidine would attenuate these alterations. Single, living skeletal muscle fibres from Xenopus laevis were injected with the Ca(2+) indicator fura 2, and incubated for 1 h prior to stimulation in 100 micro M TMZ-Ringer solution (TMZ; n = 6) or standard Ringer solution (CON; n = 6). Force and relative free cytosolic Ca(2+) concentration ([Ca(2+)](c)) were measured during continuous tetanic contractions produced every 5 s as fibres were sequentially perfused in the following manner: 3 min high extracellular P(O(2)) (159 mmHg), 15 min hypoxic perfusion (3-5 mmHg) then 3 min high P(O(2)). Hypoxia caused a decrease in force and peak [Ca(2+)](c) in both the TMZ and CON fibres, with no significant (P < 0.05) difference between groups. However, basal [Ca(2+)](c) was significantly lower during hypoxia in the TMZ group vs. the CON group. While reoxygenation generated only modest recovery of relative force and peak [Ca(2+)](c) in both groups, basal [Ca(2+)](c) remained significantly less in the TMZ group. These results demonstrated that in contracting, single skeletal muscle fibres, TMZ prevented increases in basal [Ca(2+)](c) generated during a severe hypoxic insult and subsequent reoxygenation, yet failed to protect the cell from the deleterious effects of prolonged hypoxia followed by reoxygenation.     

Dynamics and consequences of potassium shifts in skeletal muscle and heart during exercise

Since it became clear that K(+) shifts with exercise are extensive and can cause more than a doubling of the extracellular [K(+)] ([K(+)](s)) as reviewed here, it has been suggested that these shifts may cause fatigue through the effect on muscle excitability and action potentials (AP). The cause of the K(+) shifts is a transient or long-lasting mismatch between outward repolarizing K(+) currents and K(+) influx carried by the Na(+)-K(+) pump. Several factors modify the effect of raised [K(+)](s) during exercise on membrane potential (E(m)) and force production. 1) Membrane conductance to K(+) is variable and controlled by various K(+) channels. Low relative K(+) conductance will reduce the contribution of [K(+)](s) to the E(m). In addition, high Cl(-) conductance may stabilize the E(m) during brief periods of large K(+) shifts. 2) The Na(+)-K(+) pump contributes with a hyperpolarizing current. 3) Cell swelling accompanies muscle contractions especially in fast-twitch muscle, although little in the heart. This will contribute considerably to the lowering of intracellular [K(+)] ([K(+)](c)) and will attenuate the exercise-induced rise of intracellular [Na(+)] ([Na(+)](c)). 4) The rise of [Na(+)](c) is sufficient to activate the Na(+)-K(+) pump to completely compensate increased K(+) release in the heart, yet not in skeletal muscle. In skeletal muscle there is strong evidence for control of pump activity not only through hormones, but through a hitherto unidentified mechanism. 5) Ionic shifts within the skeletal muscle t tubules and in the heart in extracellular clefts may markedly affect excitation-contraction coupling. 6) Age and state of training together with nutritional state modify muscle K(+) content and the abundance of Na(+)-K(+) pumps. We conclude that despite modifying factors coming into play during muscle activity, the K(+) shifts with high-intensity exercise may contribute substantially to fatigue in skeletal muscle, whereas in the heart, except during ischemia, the K(+) balance is controlled much more effectively.     

Analysis of the membrane capacity in frog muscle

1. The membrane capacity (C(f)) was determined from the conduction velocity and the time constant of the foot of the action potential in frog's skeletal muscle.2. In normal fibres C(f) was 2.6 muF/cm(2), and the value was almost constant over a range of diameter from 55 to 140 mu.3. In fibres, in which the transverse tubular system was disconnected from the surface by the glycerol treatment, C(f) was 0.9 muF/cm(2) and was fairly constant over a range of diameter from 60 to 130 mu. The low frequency capacity in glycerol-treated fibres was 1.9 muF/cm(2).4. These results as well as those obtained at low frequencies were consistent with the electrical model proposed by Adrian, Chandler & Hodgkin (1969).5. Analysis in terms of the model and of Peachey's (1965) data on tubular dimensions led to the following quantitative conclusions. The capacities of the surface membrane (C(S)) and of the tubular wall (C(W)) are both about 1 muF/cm(2). The conductances of the surface membrane (G(S)) and tubular wall (G(W)) are ca. 0.11 and 0.03 mmho/cm(2), respectively. The conductivity of the luminal fluid in the tubules is ca. 6 mmho/cm.     

Model of electrical conductivity of skeletal muscle based on tissue structure

Recent experiments carried out in our laboratory with the four-electrode method showed that the electrical conductivity of skeletal muscle tissue depends on the frequency of the injected current and the distance between the current electrodes. A model is proposed in order to study these effects. The model takes into account the structure of the tissue on the scale of individual fibres. It discerns three main components with respect to electrical properties: (a) extracellular medium with electrical conductivity σ_e; (b) intracellular medium with electrical conductivity σ_i; (c) muscle fibre membrane with impedance Z_m. The model results show an apparent frequency dependence of the electrical conductivity of skeletal muscle tissue, as well as the way the conductivity is affected by the length the current is conducted.     

Stromal interaction molecule 1 (STIM1) regulates sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 1a (SERCA1a) in skeletal muscle

Stromal interaction molecule 1 (STIM1) mediates Ca²⁺ movements from the extracellular space to the cytosol through a store-operated Ca²⁺ entry (SOCE) mechanism in various cells including skeletal muscle cells. In the present study, to reveal the unidentified functional role of the STIM1 C terminus from 449 to 671 amino acids in skeletal muscle, binding assays and quadrupole time-of-flight mass spectrometry were used to identify proteins binding in this region along with proteins that mediate skeletal muscle contraction and relaxation. STIM1 binds to sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase 1a (SERCA1a) via this region (called STIM1-SBR). The binding was confirmed in endogenous full-length STIM1 in rabbit skeletal muscle and mouse primary skeletal myotubes via co-immunoprecipitation assay and immunocytochemistry. STIM1 knockdown in mouse primary skeletal myotubes decreased Ca²⁺ uptake from the cytosol to the sarcoplasmic reticulum (SR) through SERCA1a only at micromolar cytosolic Ca²⁺ concentrations, suggesting that STIM1 could be required for the full activity of SERCA1a possibly during the relaxation of skeletal muscle. Various Ca²⁺ imaging experiments using myotubes expressing STIM1-SBR suggest that STIM1 is involved in intracellular Ca²⁺ distributions between the SR and the cytosol via regulating SERCA1a activity without affecting SOCE. Therefore, in skeletal muscle, STIM1 could play an important role in regulating Ca²⁺ movements between the SR and the cytosol.     

Paracrine release of insulin-like growth factor 1 from a bioengineered tissue stimulates skeletal muscle growth in vitro

Bioengineered tissues transduced to secrete recombinant proteins may serve as a long-term delivery vehicle for therapeutic proteins when implanted in vivo. Insulin-like growth factor 1 (IGF1) is an anabolic growth factor for skeletal muscle that can stimulate myoblast proliferation and myofiber hypertrophy. To determine whether the release of IGF1 from an engineered bioartificial skeletal muscle (BAM) could stimulate the growth of skeletal muscle in a paracrine manner, we established an in vitro perfusion system for genetically engineered IGF1 BAMs. BAMs were bioengineered from C2C12 murine myoblasts stably transduced with a retroviral vector to synthesize and secrete IGF1 (C2-IGF1 BAMs). C2-IGF1 BAMs or nontransduced control C2 BAMs were cocultured with avian BAMS (ABAMs) in constantly perfused biochambers. During 11 days of perfusion, IGF1 levels in the C2-IGF1 BAM perfusion medium increased linearly from 1 to 20 ng/mL. The ABAMs maintained in biochambers with the C2-IGF1 BAMs had significantly more myofibers (69%, p < 0.005) and larger myofiber cross-sectional areas (40%, p < 0.001) compared to those cocultured with control C2 BAMs. These studies show that levels of IGF1 secreted from the C2-IGF1 BAMs are sufficient to produce an anabolic paracrine effect on nongenetically engineered BAMs, and the in vitro perfusion system provides a model for screening proteins effective in stimulating localized skeletal muscle growth.     

Unterschiedliche Summationsfähigkeit für vasoconstrictorische Efferenzen im Haut-, Skeletmuskel- und Mesenterialkreislauf der Katze

Summary The perfusion of the vascular beds of the skin, skeletal muscle and intestine with the animals own blood was stabilized, and the vasoconstrictor fibres leading to these areas stimulated. The correlation between the impulse frequency of stimulation and the degree of vasoconstriction is represented in the frequency response curve. The curves obtained for each vascular bed are significantly different.1. The steepness of the frequency response curves between the stimulation frequency 1–10 imp./sec shows its highest value at the vascular bed of the skin, becomes lower at that of the skeletal muscle, and reaches its smallest value at the mesenterial vascular bed. The steepness can be correlated to the capability of summation of the vascular smooth muscle.2. If the stimulation frequency exceeded a certain value, the degree of vasoconstriction became smaller. This value was found in the vascular bed of the skin at 10 imp./sec, in the mesenterial vascular bed at 25 imp./sec, and in the vascular bed of skeletal muscle at 100 imp./sec. At these values of stimulation frequency the maximum of vasoconstriction was reached. Only the frequency response curve of the skeletal muscle vascular bed showed a maximum-plateau between about 20–100 imp./sec. For the other examined areas the maximum of vasoconstriction was distinct.3. The relaxation time of the vascular smooth muscles (each one starting from the end of stimulation, ending when the control level of the resistance was reached) was significantly different in these vascular areas. The time period was found to be longest at the vascular bed of the skin, medium at that of the skeletal muscle, and smallest in the mesenterial vascular bed. On changing the stimulation frequency a maximum of relaxation time at 25–50 imp./sec for each examined vascular bed, most obviously for the skin, could be observed.These characteristic differences can be explained by: different activities of enzymes acting in the elimination of the transmitter; differences in the structure of the vascular beds; different mechanisms of the local regulation of the perfusion (e.g. autoregulatory escape, autoregulation).Regarding the frequency response curves presented in this paper and those of other effectoric systems it is obvious, that with an uniform increase of the impulse frequency in all sympathetic nerves the maximum of reaction in different organs is reached stepwise at different impulse frequencies, for example at 3 imp./sec (inotropic influence of the heart), at 25–50 imp./sec (vasoconstriction at the mesenterial vascular bed). This enables the organism to maintain a differentiated sympathetic control of the organs by one and the same modulation of the impulse frequency in all sympathetic nerves.     

超低频电磁场处理水对骨骼肌细胞糖脂代谢及线粒体功能的影响

背景：超低频电磁场处理水(简称频谱水)作用于生物体, 在很多方面能够改善生物体的生理功能,但其对骨骼肌细胞糖脂代谢和线粒体功能的影响上,还需要更进一步的理论和实验研究。 目的：探究频谱水培养对C2C12骨骼肌细胞糖脂代谢和线粒体功能的作用。 方法：采用频谱水配制的DMEM培养C2C12骨骼肌细胞96 h后收样,甲基噻唑基四唑(MTT)细胞计数法检测细胞增殖,检测培养基中葡萄糖含量、细胞内三酰甘油浓度、线粒体ATP含量,线粒体膜电位,以及葡萄糖糖转运子1、4和细胞色素C氧化酶的蛋白水平。 结果与结论：频谱水培养C2C12骨骼肌细胞96 h细胞葡萄糖消耗量增加2.4%(P < 0.05),三酰甘油浓度略有减少(P > 0.05),葡萄糖糖转运子1蛋白表达增加35.8%(P < 0.05),细胞色素C氧化酶1蛋白表达增加43.7%(P < 0.01),线粒体ATP含量和线粒体膜电位均没有明显变化(P > 0.05)。结果提示：①频谱水培养C2C12骨骼肌细胞可通过增加骨骼肌细胞膜上葡萄糖糖转运子1的含量来提高骨骼肌细胞葡萄糖利用量。②频谱水不改变正常骨骼肌细胞线粒体膜电位。③频谱水可能通过提高线粒体中细胞色素C氧化酶1的表达量而在骨骼肌细胞能量需要增加时加强线粒体的产能功能。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程      

31P and 23Na NMR spectroscopy of normal and ischemic rat skeletal muscle. Use of a shift reagent in vivo

23Na NMR spectroscopy was used 1, to define the distribution of the shift reagent for cations, triethylenetetraminehexaacetatedysprosium(III), DyTTHA3-, in the living rat; 2, to define the characteristics of the Na resonances reporting intra- and extracellular Na+ in skeletal muscle in vivo; and 3, to calculate the Na+ concentrations in the intra- and extracellular spaces of the gastrocnemius muscle during well-perfused and ischemic conditions. The concentration of DyTTHA3- infused intravenously into the jugular vein of the living rat reached a maximum value of 8-9 mM in the extracellular space of the muscle after ca 40 min of infusion. This allowed excellent discrimination of extra- and intracellular Na signals (Nao and Nai, respectively) and did not spoil the resolution of concurrent 31P NMR spectra. Infusion of shift reagent changed neither hemodynamic performance of the rat nor the high-energy phosphate content of skeletal muscle. Shift reagent enters ca 15% (v/w) of the rat body weight; this corresponds to almost all of the "fast" or rapidly permeable extracellular space. It is excreted from the body with a pseudo-first order rate constant of 0.0158 min-1. In resting muscle, we estimate that [Na+]i is 3-5 mM and, in muscle perfused with the sodium salt of the shift reagent, that [Na+]o in the fast exchangeable extracellular space is 166 mM. During 11 h of ischemia at 37 degrees C, the area of the Nai+ signal area monotonically increased sixfold. Based on estimates for maximum changes in fluid shifts reported by the decrease in the area of the Nao signal area, we calculate that the lower limit for [Na+]i after 11 h of ischemia is 27 mM. The NMR-visibility factors for the extracellular and intracellular Na+ signals are essentially the same. This study demonstrates that the shift reagent DyTTHA3- is acutely non-toxic and that the 23Na NMR spectra obtained can be used to quantitate [Na+]o and [Na+]i in tissues in vivo. Using this technique, we found that the transmembrane sodium gradient fell from ca 35 in well-perfused skeletal muscle to less than 6 during prolonged ischemia.