棉花的钾素营养诊断和钾胞施用

棉花是需钾较多的一种作物,特别在氮、磷肥用量增加的情况下,棉花对钾的需要量也相应增加,当土壤中交换性钾含量不高时,往往会造成棉花生理病害——红叶茎枯病而早衰,严重地影响产量的持续提高。 作者在1972～1975年进行了江苏省主要土类钾素供应状况和棉花钾肥试验,试验结果表明:当土壤交换性钾含量低于100ppmK时,施用钾肥有显著增产效果(增产23.5％～60％)。

带状玉米田钾肥试验

钾肥试验表明,青海地区虽然钾肥含量高,但还是难以满足带状玉米的需要,如果要增加带状玉米产量还得补充钾,且钾肥的最佳施量是300kg.hm-2。

Involvement of Calcium dependent Protein Kinases in ABA regulation of Stomatal Movement

Patch clamp techniques were employed to investigate if calcium dependent protein kinases (CDPKs) be involved in the signal transduction pathways of stomatal movement regulation by the phytohormone abscisic acid (ABA) in Vicia faba. Stomatal opening was completely inhibited by external application of 1 μmol/L ABA, and such ABA inhibition was significantly reversed by the addition of CDPK inhibitor trifluoperazine (TFP). The inward whole cell K + currents were inhibited by 60% in the presence of 1 μmol/L intracellular ABA, and this inhibition was completely abolished by the addition of CDPK competitive substrate histone Ⅲ S. The results suggest that CDPKs may be involved in the signal transduction cascades of ABA regulated stomatal movements.

胞外高钾对大鼠背根神经元超极化电流的影响

应用全细胞膜片钳技术研究了胞外高钾对大鼠背根神经元(DRG)超极化电流(Ih)的影响.结果表明,Ih随着胞外钾离子浓度的增大而增大,同时随着外加刺激电压的增高而增强.当胞外钾离子浓度[Kext]为4,8和16mmol/L时,半数激活电压V1/2分别为-98±1.9,-106±1.3(p<0.05)和-110±1.0mV(p<0.05),其对应的最大电流的峰值分别为1085±340,1576±409和2124±614pA,与4mmol/L比较,后者分别增长了45%和92%.胞外高钾使Ih激活曲线显著左移,说明高Kext改变了超极化电流的激活过程.提高细胞外钾离子浓度,可以使早期钾通道(又称快通道)的激活时间常数增大,使晚期钾通道(又称慢通道)激活时间常数减小.当胞外钾离子浓度由4mmol/L升高到8和16mmol/L时,翻转电位右移,但不具有显著性差异.结果提示,细胞外高浓度钾可增强大鼠背根神经元超极化电流Ih,改变Ih的激活过程,从而提高了神经元的兴奋性,产生不正常的动作电位,对神经细胞产生损伤.

The Effect of Benzyltetrahydropalmatine (BTHP) on Action Potentials and the Two Components of Delayed Rectifying Potassium Currents in Guinea Pig Ventricular Myocytes

The effects of BTHP on Ca 2+ independent action potential and the two components of delayed rectifier potassium currents were studied in guinea pig single ventricular myocytes by using whole cell patch clamp technique. BTHP 30 μmol·L -1 significantly prolonged APD 90 from 143±16 ms to 184±21 ms ( P 【0.01, n=5) without affecting either the RP or APA, and the APD prolonging effects of BTHP were independent of extracellular Ca 2+ . BTHP inhibited both I kr (IC 50 =7 9 μmol·L -1 ) and I ks (IC 50 =22 4 μmol·L -1 ) in a concentration dependent fashion. The results demon strated that BTHP had no obvious selectivity for I kr and I ks .

Effects of IQ_23 on the Repolarization and Both Components of the Delayed Rectifier Potassium Current in Guinea Pig Ventricular Myocytcs

Using patch clamp whole cell recording techiques, we examined the effects ofIQ_23, a benzyl-isoquinoline derivative with antiarrhythmic activities, on the action potential (AP) andpotassium currents in single guinea pig ventricular myocytes. The results showed that IQ_23 at 10, 30and 100 μmol ·L_-1 slowed the repolarization in AP dose-dependently. The APD_90 were prolonged by15%, 28% and 31% respectively. This effect did not depend on the extracellular Ca^2+. In voltageclamp mode, IQ_23 effectively blocked both the components of the delayed rectifier potassium current(I_k), i.e., I_ks and I_kr. At concentrations of 30 and 100 μmol· L^-1, IQ_23 suppressed I_ks by 21% and 26%and suppressed I_kr by 67% and 86% respectively. But even at 100 μmol·L^-1, IQ_23 had little effect onthe inward rectifier potassium current (I_k1). It is concluded: 1. IQ_23 can dose-dependently prolongAPD in the ventriculas myocytes of guinea pig, the effect does not depend on the extracellular Ca^2+; 2.IQ_23 blocks both I_ks and Ikr in the ventricular myocytes without obvious specificities between them.

Transformation of iron in pure culture process of extremely acidophilic microorganisms

Jarosite and extracellular polymer substance generated during pure culture and bioleaching process have been widely accepted the main transformation of decreasing iron in the medium.In the present work,acidophilus bioleaching organisms Ferroplasma thermophilum,Leptospirillum ferriphilum and Acidithioobacillus ferrooxidans were cultured.It was found that they can live in low pH environment,and more than10particles in each cell intracellular nano-particles are synthesized in the cells.By analyzing the morphology and chemical composition of nano-particles,they were found to contain iron,and the three microorganisms belonged to high-yielding strains.The results show that the transformation of the decreasing iron ions is not only generating jarosite,but also taken into cells and synthesizing ferruginous nano-particles.

Effects of IQ23 on the Repolarization and Both Components of the Delayed Rectifier Potassium Current in Guinea Pig Ventricular Myocytcs

Using patch clamp whole cell recording techiques, we examined the effects ofIQ23, a benzyl-isoquinoline derivative with antiarrhythmic activities, on the action potential （AP） andpotassium currents in single guinea pig ventricular myocytes. The results showed that IQ23 at 10, 30and 100 μmol ·L-1 slowed the repolarization in AP dose-dependently. The APD90 were prolonged by15%, 28% and 31% respectively. This effect did not depend on the extracellular Ca2+. In voltageclamp mode, IQ23 effectively blocked both the components of the delayed rectifier potassium current（Ik）, i.e., Iks and Ikr. At concentrations of 30 and 100 μmol· L-1, IQ23 suppressed Iks by 21% and 26%and suppressed Ikr by 67% and 86% respectively. But even at 100 μmol·L-1, IQ23 had little effect onthe inward rectifier potassium current （Ik1）. It is concluded: 1. IQ23 can dose-dependently prolongAPD in the ventriculas myocytes of guinea pig, the effect does not depend on the extracellular Ca2+; 2.IQ23 blocks both Iks and Ikr in the ventricular myocytes without obvious specificities between them.

Whole-cell recordings of calcium and potassium currents in acutely isolated smooth muscle cells

AIM： To record calcium and potassium currents in acutely isolated smooth muscle cells of mesenteric arterial branches in rats. METHODS： Smooth muscle cells were freshly isolated by collagenase digest and mechanical trituration with polished pipettes. Patch clamp technique in whole-cell mode was employed to record calcium and potassium currents. RESULTS： The procedure dissociated smooth muscle cells without impairing the electrophysiological characteristics of the cells. The voltage-gated Ca^2＋ and potassium currents were successfully recorded using whole-cell patch clamp configuration. CONCLUSION： The method dissociates smooth muscle cells from rat mesenteric arterial branches. Voltage-gated channel currents can be recorded in this preparation.

Effects of unsaturated fatty acids on calcium-activated potassium current in gastric myocytes of guinea pigs

AIM: To investigate the effects of exogenous unsaturated fatty acids on calcium-activated potassium current [IK(Ca)] in gastric antral circular myocytes of guinea pigs. METHODS: Gastric myocytes were isolated by collagenase from the antral circular layer of guinea pig stomach. The whole-cell patch clamp technique was used to record /K(Ca) in the isolated single smooth muscle cells with or without different concentrations of arachidonic acid (AA), linoleic acid (LA), and oleic acid (OA). RESULTS: AA at concentrations of 2,5 and 10 μmol/L markedly increased IK(Ca) in a dose-dependent manner. LA at concentrations of 5, 10 and 20 μmol/L also enhanced /K(Ca) in a dose-dependent manner. The increasing potency of AA, LA, and oleic acid (OA) on /K(Ca)at the same concentration (10μmol/L) was in the order of AA>LA>OA. AA (10 μmol/L)-induced increase of Ik(ca) was not blocked by H-7 (10 μmol/L), an inhibitor of protein kinase C (PKC), or indomethacin (10 μmol/L), an inhibitor of the cyclooxygenase pathway, and 17-octadecynoic acid (10 μmol/L), an inhibitor of the cytochrome P450 pathway, but weakened by nordihydroguaiaretic acid (10μmol/L), an inhibitor of the lipoxygenase pathway. CONCLUSION: Unsaturated fatty acids markedly increase Ik(Ca), and the enhancing potencies are related to the number of double bonds in the fatty acid chain. The lipoxygenase pathway of unsaturated fatty acid metabolism is involved in the unsaturated fatty acid-induced increase of IK(Ca) in gastric antral circular myocytes of guinea pigs.

Aberrant expression of ether à go-go potassium channel in colorectal cancer patients and cell lines

AIM: To study the expression of ether à go-go (Eag1) potassium channel in colorectal cancer and the relation- ship between their expression and clinico-pathological features. METHODS: The expression levels of Eag1 protein were determined in 76 cancer tissues with paired non- cancerous matched tissues as well as 9 colorectal adenoma tissues by immunohistochemistry. Eag1 mRNA expression was detected in 13 colorectal cancer tissues with paired non-cancerous matched tissues and 4 colorectal adenoma tissues as well as two colorectal cancer cell lines (LoVo and HT-29) by reverse transcription PCR. RESULTS: The frequency of positive expression of Eag1 protein was 76.3% (58/76) and Eag1 mRNA was 76.9% (10/13) in colorectal cancer tissue. Expression level of Eag1 protein was dependent on the tumor size, lymphatic node metastasis, other organ metastases and Dukes’ stage (P < 0.05), while not dependent on age, sex, site and degree of differentiation. Eag1 protein and mRNA were negative in normal colorectal tissue, and absolutely negative in colorectal adenomas except that one case was positively stained for Eag1 protein. CONCLUSION: Eag1 protein and mRNA are aberrantly expressed in colorectal cancer and occasionally expressed in colorectal adenoma. The high frequency of expression of Eag1 in tumors and the restriction of normal expression to the brain suggest the potential of this protein for diagnostic, prognostic and therapeutic purposes.

NONLINEAR PROPERTY MEMBRANE RECTIFIER POTASSIUM CHANNEL AND INHIBITORY EFFECTS OF OXYGEN FREE RADICAL

There are at least eight kinds of different potassium channels on cardiac cell membrane.This paper presents a nonlinear property membrane outward current going rectifying potassium channel and the inhibitory effects of oxygen free radical on this channel.The current-voltage relation of this nonlinear-membrane can be defined by an equation I= 8a3/(0.01v2+ 4a2)2 and the maximum conductance of this channel is-75.3 PS.

Changes of Ca^2+ activated potassium channels and cellular proliferation in autogenous vein grafts

Objective: To investigate changes of Ca2+ activated potassium channels (KCa) in autogenous vein grafts. Methods: Contraction of venous ring was measured by means of perfusion in vitro. The intimal rabbits proliferation of vascular and proliferation of cultured smooth muscle cells(vascular smooth muscle cells, VSMCs)were observed by the means of computerised image analysis and MTT method respectively. Furthermore, whole cell mode of patch clamp was used to record KCa of VSMCs isolated from autogenous vein grafts. Results: One week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation (P<0.05, n=8 vs control), and they was more enhanced 4 weeks after vein transplantation (P<0.01, n=8 vs control).TEA(blocker of Ca2+ activated potassium channels)increased MTT A490 nm value of VSMCs from femoral vein in a dose dependent manner(P<0.05, n=8). KCa current density was significantly attenuated in VSMCs from autogenous vein grafts (1-4) week after transplantation(P<0.05, n=5).Conclusion: KCa is inhibited in autogenous vein graft, which account for vasospasm and intimal proliferation.

Effects of allocryptopine on outward potassium current and slow delayed rectifier potassium current in rabbit myocardium

Objective Allocryptopine （ALL） is an effective alkaloid of Corydalis decumbens （Thunb.） Pers. Papaveraceae and has proved to be an- ti-arrhythmic. The purpose of our study is to investigate the effects of ALL on transmural repolarizing ionic ingredients of outward potassium current （Ito） and slow delayed rectifier potassium current （IKs）. Methods The monophasic action potential （MAP） technique was used to record the MAP duration of the epicardium （Epi）, myocardium （M） and endocardium （Endo） of the rabbit heart and the whole cell patch clamp was used to record/to and IKs in cardiomyocytes of Epi, M and Endo layers that were isolated from rabbit ventricles. Results The effects of ALL on MAP of Epi, M and Endo layers were disequilibrium. ALL could effectively reduce the transmural dispersion of repolarization （TDR） in rabbit transmural ventricular wall. ALL decreased the current densities of/to and IKs in a voltage and concentration dependent way and narrowed the repolarizing differences among three layers. The analysis of gating kinetics showed ALL accelerated the channel activation ofIto in M layers and partly inhibit the channel openings of/to in Epi, M and Endo cells. On the other hand, ALL mainly slowed channel deactivation of IKs channel in Epi and Endo layers without affecting its activation. Conclusions Our study gives partially explanation about the mechanisms of tmnsmural inhibition of/to and IKs channels by ALL in rabbit myocardium. These findings provide novel perspective regarding the anti-arrhythmogenesis application of ALL in clinical settings.

Characteristics of Transient Outward Potassium Channel Exposed to 3 mT Static Magnetic Field

Acutely isolated mouse hippocampal CA3 pyramidal neurons were exposed to 3 mT static magnetic field,and the characteristics of transient outward K+ channel were studied using the whole-cell patch-clamp technique.The experiment revealed that the amplitude of transient outward potassium channel current was reduced.The maximum activated current densities of control group and exposure group were 163.62±20.68 pA/pF and 98.74±16.57 pA/pF(n=12,P<0.01) respectively.The static magnetic field exposure affected the activation and inactivation process of transient outward potassium channel current.Due to the magnetic field exposure,the half-activation voltage of the activation curves changed from 5.59±1.96 mV to 27.87±7.24 mV(n=12,P<0.05) ,and the slope factor changed from 19.43±2.11 mV to 25.87±4.22 mV(n=12,P<0.05) .The half-inactivation voltage of the inactivation curves also changed from-56.09±0.89 mV to-57.16±1.10 mV(n=12,P>0.05) and the slope factor of the inactivation curves from 8.69±0.80 mV to 10.87±1.02 mV(n=12,P<0.05) .The results show that the static magnetic field can change the characteristics of transient outward K+ channel,and affect the physiological functions of neurons.

Migration-associated secretion of melanoma inhibitory activity at the cell rear is supported by KCa3.1 potassium channels

Malignant melanoma, characterized by invasive local growth and early formation of metastases, is the most aggressive type of skin cancer. Melanoma inhibitory activity （MIA）, secreted by malignant melanoma cells, interacts with the cell adhesion receptors, integrins a4131 and 05131, facilitating cell detachment and promoting formation of me- tastases. In the present study, we demonstrate that MIA secretion is confined to the rear end of migrating cells, while in non-migrating cells MIA accumulates in the actin cortex. MIA protein takes a conventional secretory pathway including coat protein complex I （COPI）- and coat protein complex II （COPII）-dependent protein transport to the cell periphery, where its final release depends on intracellular Ca2＋ ions. Interestingly, the Ca2＋-activated K＋-channel, subfamily N, member 4 （KCa3.1）, known to be active at the rear end of migrating cells, was found to support MIA secretion. Secretion was diminished by the specific KCa3.1 channel inhibitor TRAM-34 and by expression of dominant- negative mutants of the channel. In summary, we have elucidated the migration-associated transport of MIA protein to the cell rear and also disclosed a new mechanism by which KCa3.1 potassium channels promote cell migration.

Upregulated voltage-gated potassium channel Kvl.3 on CD4＋CD28null T lymphocytes from patients with acute coronary syndrome

Objective The purpose of our study is to observe the voltage-gated potassium channel Kvl.3 expressed on CD4＋CD28~ T cells from the peripheral blood of acute coronary syndrome （ACS） patients by the patch clamp technique. Methods Kvl.3 potassium channels expression from 17 patients with ACS and 11 healthy age-match controls was detected in single cell（CD4＋CD28null T cells and CD4＋CD28＋T cells） by fluorescence mieroscopy and patch clamp. Results The percentage of CD4＋CD28mullT cells was higher in the ACS patients [（6.97±2.05）%] than that in the controls [（1.38±0.84）%, P〈0.05]. The concentration of hsCRP was directly correlated with the number of the CD4~CD28nul~ T cells in the ACS patients （r=0.52, P〈0,05）. The conductance （6.89±1.17ns vs 3.36±0.66ns）, dens （1.95±0.80 μm2 vs 1.13±0.57 μm2） and numbers （574.5±97.6 n/cell vs. 280.3±55.3 n/cell） of the Kv1.3 channels on the CIM＋CD28null T cells were significantly higher than those on the CD4＋CD28＋ T cells （all P〈0.01） in ACS patients, but were similar on CD4＋CD28＋T betweenACS patients and controls. Conclusion The CD4＋CD28nullT cells and the numbers of Kvl.3 channels on the CD4＋CD28nullT cells from patients with ACS are significantly upregulated and might contribute to the pathogenesis of ACS （d Geriatr Cardio12010; 7：40-46）.

Effect of genistein on voltage-gated potassium channels in guinea pig proximal colon smooth muscle cells

AIM： To investigate the action of genistein （GST）, a broad spectrum tyrosine kinase inhibitor, on voltagegated potassium channels in guinea pig proximal colon smooth muscle cells. METHODS： Smooth muscle cells in guinea pig proximal colon were enzymatically isolated. Nystatin-perforated whole cell patch clamp technique was used to record potassium currents including fast transient outward current （Ikto） and delayed rectifier current （Ikdr）, tWO of which were isolated pharmacologically with 10 mmol/L tetraethylammonium or 5 mmol/L 4-aminopyridine. Contamination of calcium-dependent potassium currents was minimized with no caldum and 0.2 mmol/L CdCl2 in an external solution. RESULTS： GST （10-100 μmol/L） reversibly and dosedependently reduced the peak amplitude of Ikto with an IC50 value of 22.0±6.9 μmol/L. To a lesser extent, Ikdr, was also inhibited in both peak current and sustained current. GST could not totally block the outward potassium current as a fraction of the outWard potassium current, which was insensitive to GST. GST had no effect on the steady-state activation （n =6） and inactivation kinetics （n =6） of Ikto. Sodium orthovanadate （1 retool/L）, a potent inhibitor of tyrosine phosphatase, significantly inhibited GST-induced inhibition （P〈 0.05）. CONCLUSION： GST can dose-dependently and reversibly block voltage-gated potassium channels in guinea pig proximal colon smooth muscle cells.

Effects of Glucose on Transmembrane Ionic Current of Ventricular Myocytes in Guinea Pig

Aim To determine the effects of glucose on APD, I_(K1) , I_K , I_(Ca-L), ofventricular myocytes in guinea pigs, Methods Whole-cell patch-clamp technique was used to record thechanged action potential ionic current induced by glucose of single cell in guinea pig ventricularmyocytes, to compare the action of 0, 10 and 20 mmol·L^(-1) glucoses on trans-membrane ioniccurrent. Results (1) Compared with 10 mmol·L^(-1) glucose concentrations, 0 and 20 mmol·L^(-1)glucose both shortened APD of ventricular myocytes ( P < 0.05). (2) The inward components ofI_(K1) density were maximal when the glucose concentration was at 10 mmol·L^(-1) . Normalized Ⅰ -Ⅴ relationships showed that both 0 and 20 mmol·L^(-1) glucose produced a left-shift of Ⅰ - Ⅴcurve. The reverse potential changed from - 72.4 mV to - 64.6 mV. (3) Compared with 10 mmol·L^(-1),both 0 and 20 mmol·L^(-1) glucose markedly increased the I_(Ca-L) amplitude and density. TheI_(Ca-L) current density was ( - 8.035 +- 0.82) pA/pF ( n = 8) at a test potential of 10 mV when theglucose concentration was 10 mmol·L^(-1) . But its current density decreased to ( - 5.45 +- 0.67)pA/pF and ( - 6.50 +- 0.56) pA/pF when glucose concentrations were 0 and 20 mmol·L^(-1) ,respectively. (4) The current densities of I_K were (18.96+-2.86) pA/pF, (8.66 +-1.87) pA/pF, and(15.32 +- 3.12) pA/pF, at + 70 mV for 0, 10 and 20 mmol·L^(-1) glucoses, respectively. ConclusionGlucose in different concentrations has different effects on APD, I_(K1), I_K, and I_(Ca-L) ofsingle ventricular myocyte in guinea pigs. There are similar actions of 0 and 20 mmol· L^(-1)glucoses on the transmembrane ionic current of ventricular myocytes in guinea pigs.

ATP sensitive K^+ channel may be involved in the protective effects of preconditioning in isolated guinea pig cardiomyocytes

Objective To develop a cellular model of preconditioning by a brief period of hypoxia in isolated guinea pig cardiomyocytes and to determine whether or not an ATP sensitive K+ (KATP) channel is involved in ischemic preconditioning. Methods Single myocytes were isolated from the ventricle of adult guinea pigs. The experimental chamber allowed the cells to be exposed to low O2 pressure. During hypoxic preconditioning, the cells were equilibrated with normaxic solution for 10 minutes and then exposed to hypoxia for 5 minutes, followed by 10 minutes of reoxygenation. The cells were then subjected to 20-180 minutes of hypoxia and reoxygenation. Ionic currents were studied with the patch clamp technique in whole-cell and cell-attached configurations. Results A 5-minute hypoxic preconditioning offered a significant protection from cell injury in subsequent hypoxia-reoxygenation. After a latency of more than 15 minutes, hypoxia induced a time-independent outward K+ current which could be blocked by 5?μmol/L glibenclamide. At 10?mV, the current increased from 78±15?pA to 1581±153?pA (P<0.01, n=18). However, the latency to develop KATP channel currents (IKATP) was greatly shortened in preconditioned cells, and the current was increased acceleratively. At 10?mV, the current more than 4?nA was recorded in preconditioning cells. In the single channel recordings, the time interval from the first channel opening to maximum opening was also markedly abbreviated in preconditioned cells. Conclusion Isolated guinea pig cardiomyocytes can be preconditioned with a brief period of hypoxia. This hypoxic preconditioning may modify the KATP channel, and make the channel open more readily during the second hypoxia.