首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
AIM:To clarify the role of Cl- in regulatory volume decrease (RVD) of nasopharyngeal carcinoma cells (CNE-2Z).METHODS:Analysis of living cell images was used to detect the volume changes following exposure to hypotonic solution. Iron replacement and block of iron channels were also applied in the present study. RESULTS:Extracelluar hypotonic treatment made the cells swell and induced RVD. The RVD was correlated positively to the swelling in the range of 160-230 mOsmol/L. Substitution of gluconate for Cl- in perfusing solutions markedly increased RVD. Depletion of cellular Cl- abolished, and chloride channel blockers inhibited RVD. CONCLUSION:Cl- is the key iron to establish the RVD in CNE-2Z cells. Activation of Cl- channels and Cl- efflux are the major mechanisms of RVD.  相似文献   

2.
AIM:To investigate the role of K+ channels in the decreased hypoxic pulmonary vasoconstriction(HPV) in chronic hypoxic rats. METHODS:Blockers of three kinds of K+ channels, 4-AP(voltage dependent K+ channel blocker), TEA(Ca2+ activated K+ channel blocker), GLIB(ATP sensitive K+ channel blocker) were used in isolated perfused rat lungs to detect the role of K+ channels in HPV. RESULTS:In normal rats, 4-AP and TEA, but not GLIB, both elicited a significant increase in pulmonary artery baseline pressure, and also potentiated the acute hypoxic pulmonary vasoconstriction. In chronic hypoxic rats, the HPV is significantly decreased, while 4-AP, TEA, GLIB all elicited a significant but smaller increase in pulmonary artery baseline pressure. Additionally, all these three blockers potentiated the HPV stronger in chronic hypoxic rats than in control rats. CONCLUSION:The opening of Kv, KCa, KATP might modulate the hypoxic pulmonary vasoconstriction in isolated rat lungs, and the increase in this modulation by potassium channel in chronic hypoxic rats might play a role in its decrease in HPV.  相似文献   

3.
AIM:To investigate the volume-activated chloride currents and regulatory volume decrease(RVD) induced by hypotonic challenges in rat embryonic myocardial cell line H9c2. METHODS:The technique of whole-cell patch-clamp was used to record the chloride currents induced by hypotonic challenges and to clarify the properties of the currents in H9c2 cells. The changes of cell volume were observed by the technique of real-time living cell imaging, and the roles of chloride channels in RVD were analyzed. RESULTS:A weak background current was recorded in H9c2 cells under isotonic condition. Extracellular application of 47% hypotonic solution rapidly activated an outward rectified current, which did not exhibit time-and voltage-dependent inactivation with the current density of(47.77±3.80) pA/pF at +80 mV and(-33.36±2.80) pA/pF at-80 mV. The reversal potential was(-9.02±0.61) mV, closed to the calculated equilibrium potential for Cl-(-0.9 mV). The current was volume-sensitive and was completely suppressed by 47% hypertonic solution. In addition, chloride channel blockers tamoxifen(20 μmol/L), 5-nitro-2-(3-phenylpropylamino) benzoic acid(NPPB,100 μmol/L) and ATP(10 mmol/L) significantly inhibited the current with different inhibitory ratios. The phenomenon of RVD was also observed in H9c2 cells under the condition of perfusion with 47% hypotonic solution. The chloride channel blocker NPPB at concentration of 100 μmol/L completely inhibited the RVD process. CONCLUSION:The volume-activated chloride channels, which are activated by extracellular hypotonic challenges, play an important role in the process of regulatory volume decrease in H9c2 cells.  相似文献   

4.
AIM: The roles of Cl-channels in regulatory volume decrease (RVD), cell proliferation and cell cycle progression in nasopharyngeal carcinoma cells (CNE-2Z) were investigated. METHODS: Image analysis of living cells was used to detect the volume changes following exposure to hypotonic solutions. Cell viability was determined by the trypan blue assay. MTT method was applied to detected cell proliferation. The effect of the blocker on the cell cycle distribution was monitored by the flow cytometry. RESULTS: 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) inhibited RVD and cell proliferation in a dose-dependent manner. NPPB at the concentration of 100 μmol/L arrested cells in G1 phase (G1 population increased from 54% to 71% at 48 h after treatments), but did not significantly alter cell viability. CONCLUSION: Block of chloride channels suppressed cell proliferation by arresting cells in G1 phase. The results suggest that activation of Cl-channels and RVD is necessary for facilitating cells to proceed to the S phase from G1 phase and maintaining cell proliferation.  相似文献   

5.
FU Qing-jie  ZOU Fei 《园艺学报》2002,18(5):466-468
AIM:To investigate the effect of Ba2+ concentration on L-type of Ca2+ channel in hypothalamic neurons.METHODS:The cell acute isolation technique and cell-attached patch-clamp technique were used.RESULTS:The slope conductance of L-type Ca2+ channel were 28.6 pS (110 mmol/L) and 19.1 pS (10 mmol/L), and the open probability (NP0) obviously different with different Ba2+ concentration as carrier. CONCLUSION:Ba2+ concentration had the obvious effect on the L-type Ca2+ channel.  相似文献   

6.
AIM: To observe the effect of high temperature on the delayed rectifier K+ channel(IK) in hypothalamus neurons METHODS: The kinetic properties of I K were measured by cell-attached mode of patche-clamp technique RESULTS: The conductance, long-term open constant(τ o2) and open probability(Po) of IK increased with increase of temperature (P <0.05), while more burst open and multi-order open were recorded Many types of currents occurred after heat stress at 43℃,and voltage-dependent property reduced and even depressed CONCLUSIONS: The activating action of IK might be affected obviously by high temperature, the coupling between I K and body fever or heatstroke remained to be established.  相似文献   

7.
15 years ago, Noma first applicated the patch clamp technique to CN-treated mamammalian heart cells, e-vealed specific K+ channels which were depressed by intracellular ATP at level greater than 1 mNl.He suggested the ATP-sensitive channels are important for regulating cellular energy metabolism in the control of membrane exitability. Recent studies supported the hypothesis and suggested that ATP- sensitive channels play an important role in hypoxia, myocardial ischemia/reperfusion and is chemic preconditioning  相似文献   

8.
AIM:To study the blocking effects of extracellular Cd2+ on the inward rectifier potassium channel (IRK1) expressed in the Xenopus oocytes. METHODS:Two-microelectrode voltage clamp (TEV) method was used. RESULTS:Cd2+ can concentration-, time- and voltage dependently block IRK1 instantaneous currents ( 1.5 ms after voltage applied ) when external Cd2+ concentration is 0, 0.1, 0.15, 0.3, 0.9, 2.7 or 5.4 mmol/L with K+ concentration fixed to 90 mmol/L. Cd2+ almost has no effect on the gating property and outward currents of IRK1. Cd2+ can concentration-dependently increase the normalized conductance of IRK1. IRK1 can not permeate Cd2+ because reverse potential did not change. Three exponential fitting analyze indicates that time constant is not changed with the change in Cd2+ concentration. This shows that the inhibitory effects of Cd2+ may be caused by surface potential or the blocking site of Cd2+ is at the surface of the channel. Because external Cd2+ can not inhibit IRK1 macroscopic currents more powerfully when external Cd2+ concentration is lower. These mean that external Cd2+ does not work through surface potential mechanism.CONCLUSION:Cd2+ is considered as one of the fast open channel blockers of IRK1 and its blocking site is at the surface of the channel.  相似文献   

9.
AIM:To study the changes of K+ channels of outer hair cells in guinea pig cochlea with streptomycin ototoxicity. METHODS:Auditory brainstem responses (ABR) and whole-cell patch clamp techniques were used.RESULTS:(1) The body weight of guinea pigs with streptomycin ototoxicity decreased significantly; (2) The ABR threshold markedly increased in streptomycin group (Ⅱ,Ⅲ);(3)The number of dissociated outer hair cells of guinea pigs (Ⅱ,Ⅲ) was lower than that of control (Ⅰ); (4) Streptomycin decreased the Ca2+-sensitive K+ currents and delayed outward K+ currents distinctly; (5) There was no significant difference of K+ currents between Ⅰ and Ⅱ/Ⅲ. CONCLUSION:These results suggest that the inhibition of K+ channels is the basis of streptomycin ototoxicity, but not the direct reason for cell death.  相似文献   

10.
Pulmonary hypertension induced by high pulmonary blood flow involves a variety of complex mechanisms, including endothelial damage, pulmonary artery smooth muscle relaxation-contraction disorder and vascular remodeling. Besides, the factor of ion channels in pulmonary artery smooth muscle cells is also highly correlated to vasoconstriction. In recent years, many studies have shown that activation of Ca2+-activated Cl- channels is responsible for the membrane depolarization of pulmonary artery smooth muscle cells, and plays an important role in the regulation of vascular tone and vasoconstriction. This article reviews the biophysical and pharmacological characteristics of Ca2+-activated Cl- channels as well as the influence of Ca2+-activated Cl- channels in high pulmonary blood flow-induced pulmonary hypertension.  相似文献   

11.
AIM: To observe the effects of hydroxysafflor yellow A (HSYA) on the relaxation of isolated rat coronary artery (RCA) rings and its relationship with voltage-gated K+ (Kv) channels. METHODS: The vascular tension was recorded with a wire myograph. The Kv currents of freshly isolated RCA smooth muscle cells were assessed with whole-cell patch clamp. The protein expression levels of Kv1.2 and Kv1.5 in RCA smooth muscle cells were assayed by Western blot. RESULTS: HSYA (10 μmol/L and 30 μmol/L) led to relaxation of RCA precontracted by 60 mmol/L KCl or 0.1 mmol/L U46619 (P<0.05), but the effect showed no statistical difference between endothelium-intact and endothelium-denuded groups (P>0.05). HSYA (3 μmol/L, 10 μmol/L and 30 μmol/L) significantly increased the maximal Kv currents of RCA smooth muscle cells (P<0.05). HSYA (10 μmol/L and 30 μmol/L) increased the protein expression of Kv1.2 and Kv1.5 (P<0.05). CONCLUSION: HSYA relaxes isolated RCA in an endothelium-independent manner. The vasodilatory effect of HSYA may be related to activation of the myocyte Kv channels.  相似文献   

12.
Chloride channels distribute widely in the body, and participate in many physiological actions and regulatory processes. Based on their physiological roles and molecular structures, six kinds of chloride channels have been identified: (1) The chloride channels family; (2) Cystic fibrosis transmembrane conductance regulator; (3) Swelling-activated chloride channels; (4) Calcium-activated chloride channels; (5) The p64 (CLIC) gene family; (6) γ-aminobutyric acid and glycine receptors. The chloride channels do exist in platelets, and their appearances are dependent on the presence of intracellular calcium. Blocking agents of chloride channels inhibit the thrombin-activated platelet aggregation and the elevation of the intracellular calcium concentration in a dose-dependent manner. It is suggested that chloride channels play a role in the activation of platelets. In addition, chloride channels act on both the cell volume regulation and the intracellular pH regulation in platelets.  相似文献   

13.
AIM:To study the current density and function of Na+ channel in cells from the epicardial border zone of the 1-week infarcted rabbit heart.METHODS:Rabbits were infarcted by ligation of the left anterior descending coronary artery.1 week later, INa was recorded using whole cel patch-clamp techniques in ventricular my ocytes from infarcted heart(IZs)and compared with the INa from noninfarcted heart(NZs).RESULTS:Peak INa current density(at -30 mV) was significantly reduced in IZs(22.48±4.62 PA/PF, n=14) compared with NZs(45.50±5.33 PA/PF, n=12), P＜0.01;V0.5 of the availability curve(I/Imax curve)was shifted significantly in the hyperpolarizing direction in IZs(-89.1±5.6 mV, n=6) compared with NZs (-76.2±5.3 mV, n=5), P＜0.05.Recovery of INa from inactivation was significantly slower in IZs.CONCLUSIONS:INais reduced, and its kinetics are altered in IZs.These changes may underlie the altered excitability and postrepolarization refractoriness of ventricular fibers of the IZs, thus contributing to reentrant arrhymias in the infarcted heart.  相似文献   

14.
AIM：To investigate the type of chloride channel activated by cisplatin in poorly differentiated nasopharyngeal carcinoma cells (CNE-2Z cells). METHODS：The technique of whole-cell patch-clamp was used to investigate the role of Ca2+ in the activation of cisplatin-activated chloride currents and to analyze the effect of hypertonic stress on these currents in CNE-2Z cells. RESULTS：Chloride currents were induced when the cells were exposed to the calcium-free cisplatin solution, showing the similar density to the currents induced by cisplatin with the presence of extracellular calcium. However, the latency and the peak time of cisplatin-activated currents in the absence of extracellular calcium were prolonged. The activation of cisplatin-activated chloride currents was insensitive to the depletion of intra- and extracellular calcium. Calcium channel antagonist nifedipine had no effect on the cisplatin-activated chloride currents, while hypertonic solution completely inhibited those currents. CONCLUSION：The cisplatin-activated chloride currents are independent on intra/extracellular calcium. The chloride channels activated by cisplatin are not calcium-activated chloride channels, but are probably volume-sensitive chloride channels.  相似文献   

15.
AIM: To analyze the possibility that volume-activated chloride channel (VACC) exists in tumor stem cells. METHODS: CD133+ cells were purified by magnetic cell separation (MACS) system from non-small-cell lung cancer cell line A549. The purity of the cells was detected by flow cytometry. VACC current was recorded with whole-cell patch-clamp. RESULTS: The purity of CD133+ cells isolated from A549 by MACS was 92.14%. VACC current was recorded in the 22/40(55%) CD133+ cells of A549 by whole-cell patch-clamp. CONCLUSION: VACC exists in CD133+ lung cancer stem cells.  相似文献   

16.
AIM: To investigate whether the opening of ATP-sensitive K+(KATP) channels protects H9c2 cardiac cells against high glucose(HG)-induced injury and inflammation by inhibiting the Toll-like receptor 4(TLR4)/nuclear factor-κB(NF-κB) pathway. METHODS: The protein levels of TLR4 and NF-κB p65 were determined by Western blot. The levels of interleukin-1β(IL-1β) and tumor necrosis factor-α(TNF-α) were detected by ELISA. The cell viability was measured by CCK-8 assay. Mitochondrial membrane potential(MMP) was examined by rhodamine 123(Rh 123) staining followed by photofluorography. The intracellular levels of reactive oxygen species(ROS) were detected by 2', 7'-dichlorfluorescein- diacetate(DCFH-DA) staining followed by photofluorography. The number of apoptotic cells was observed by Hoechst 33258 nuclear staining followed by photofluorography. RESULTS: After the H9c2 cardiac cells were treated with HG(35 mmol/L glucose) for 24 h, the protein levels of TLR4 and phosphorylated NF-κB p65(p-NF-κB p65) were significantly increased. Pretreatment of the cells with 100 μmol/L diazoxide(DZ, a KATP channel opener) for 30 min before exposure to HG considerably blocked the up-regulation of the TLR4 and p-NF-κB protein levels induced by HG. Moreover, co-treatment of the cells with 30 μmol/L TAK-242(an inhibitor of TLR4) obviously inhibited the HG-induced up-regulation of the p-NF-κB p65 protein level. On the other hand, pretreatment of the cells with 100 μmol/L DZ had a clear myocardial protection effect, which attenuated the HG-induced cytotoxicity, inflammatory response, mitochondrial damage, oxidative stress and apoptosis, evidenced by an increase in the cell viability, and decreases in the levels of IL-1β and TNF-α, MMP loss, ROS generation and the number of apoptotic cells. Similarly, co-treatment of H9c2 cardiac cells with 30 μmol/L TAK-242 or 100 μmol/L PDTC(an inhibitor of NF-κB) and HG for 24 h also obviously reduced the above injuries and inflammation induced by HG.CONCLUSION: The opening of KATP channels protects H9c2 cardiac cells against HG-induced injury and inflammation by inhibiting the TLR4/NF-κB pathway.  相似文献   

17.
AIM: To investigate the effect of quercetin on endothelin-1-induced T-type calcium channel(TCC) expression in primary cultured human umbilical arterial smooth muscle cells for exploring the protective role of quercetin in cardiovascular system. METHODS: Human umbilical arterial smooth muscle cells were verified by immunocytochemistry. The cells in 2-3 passages were used and randomly divided into control group, quercetin alone group, model group and experimental group. The cells in control group were cultured without any drugs for 24 h. The cells in quercetin alone group were cultured with 80 μmol/L quercetin for 24 h. The cells in model group were cultured with ET-1 at the concentration of 100 nmol/L for 24 h. The cells in experimental groups were pretreated with quercetin for 1 h, then coincubated with 100 nmol/L ET-1 for 24 h. The concentrations of quercetin used in this study were 20, 40and 80 μmol/L, respectively. The expression of α1G, a TCC major subunit, was assayed at mRNA and protein levels by RT-PCR and Western blotting, respectively. The TCC currents(IcaT) were detected by the technique of whole-cell patch-clamp. RESULTS: Compared with control and experimental group, ICaT density (P<0.01) and the expression of α1G at mRNA (P<0.05) and protein (P<0.01) levels in model group were significantly increased. No significant difference in the results of quercetin alone group and control group was observed. CONCLUSION: The protective roles of quercetin in cardiovascular functions are related to the depressive effects of quercetin on ET-1-induced increase in both ICaT density and the expression of α1G at mRNA and protein levels in cultured human vascular smooth muscle cells.  相似文献   

18.
AIM: To explore the correlation between development of CD4+CD25+ regulatory T cells (CD4+CD25+ Tr) and thymus CD4-CD25+ cells. METHODS: The ratios of CD4+CD25+ regulatory T cells to CD4+ T cells in thymus, spleen, lymph node and peripheral blood of mice from birth to mature and also the ratios of CD4-CD25+ cells to CD4- T cells in thymus were measured by flow cytometry. Purified CD4+CD25+ T cells and CD4+CD25- T cells were labeled with CFDA-SE, and then stimulated with various kinds of stimulators. RESULTS: The percentages of CD4+CD25+ Tr in mouse spleen, lymph nodes and peripheral blood increased gradually, but not in thymus, from day one to week 10 of the age with rapid rising from day one to week 1. The percentages of CD4-CD25+ cells in mouse thymus were quite high on day one after birth, and decreased rapidly from day one to week 1. Both CD4+CD25+ Tr and CD4+CD25- T cells showed no proliferation in response to ConA, while CD4+CD25+ Tr showed a transient enlargement of cell size. Both CD4+CD25+ Tr and CD4+CD25- T cells underwent proliferation in response to PDB plus ionomycin. CD4+CD25- T cells, but not CD4+CD25+ Tr, showed a proliferative response to the stimulation of coated anti-CD3 plus soluble anti-CD28 antibody, however, CD4+CD25+ Tr showed significant proliferation and CD4+CD25- T cells showed a stronger response in addition of high dose of IL-2. CONCLUSION: The thymus CD4-CD25+ cells are probably the precursor of CD4+CD25+ Tr during cell development.  相似文献   

19.
Activating mutation in the KCNJ11 gene encoding Kir6.2 subunit of adenosine triphosphate (ATP)-sensitive potassium (KATP) channel gives rise to intermediate developmental delay, epilepsy and neonatal diabetes (iDEND) syndrome, a rare hereditary endocrine metabolic disorder characterized by neonatal diabetes accompanied by developmental delay and muscle weakness, but no epilepsy. The Kir6.2 Val59→Met59 (V59M) activating mutation is the common cause of iDEND syndrome (>50%). Activating mutation causes iDEND syndrome by inhibiting normal closure of ATP-sensitive K+ channel, which leads to reduce insulin secretion. Most of such patients are more sensitive to sulfonylurea. High blood-brain barrier permeability and sulfonylurea receptor 1 (SUR1)-specific drugs are expected to become a major therapy.  相似文献   

20.
AIM: To investigate the role of intracellular free Ca2+ concentration (［Ca2+］i) in the regulation of calcium-activated chloride (ClCa) channels in pulmonary artery smooth muscle cells (PASMCs) of rats under normoxic, acute and chronic hypoxic conditions. METHODS: Acute hypoxia-induced contraction was observed in rat pulmonary artery by using routine blood vascular perfusion in vitro. The fluorescence Ca2+ indicator Fura-2/AM was used to observe ［Ca2+］i of rat PASMCs in normal and chronic hypoxic condition. The influences of ClCa channels on PASMCs proliferation were assessed by MTT assay. RESULTS: (1) The ClCa channel blockers niflumic acid (NFA) and indaryloxyacetic acid (IAA-94) produced inhibitory effects on acute hypoxia-evoked contractions in pulmonary artery. (2) Under chronic hypoxic condition, ［Ca2+］i was increased. In normoxic condition, ［Ca2+］i was (123.63±18.98) nmol/L, and in hypoxic condition, ［Ca2+］i was (281.75±16.48)nmol/L (P<0.01). (3) In normoxic condition, ［Ca2+］i had no significant change and no effect on ClCa channels was observed (P>0.05). (4) Chronic hypoxic increased ［Ca2+］i which opened ClCa channels. The NFA and IAA-94 blocked them and decreased ［Ca2+］i from (281.75±16.48)nmol/L to (117.66±15.36)nmol/L (P<0.01). (5) MTT assay showed that in chronic hypoxic condition NFA and IAA-94 decreased the value of absorbing light degree (A value) from 0.459±0.058 to 0.224±0.025 (P<0.01). CONCLUSION: Hypoxia increased ［Ca2+］i which opened ClCa channels and had a positive-feedback to ［Ca2+］i. This may play an important role in hypoxic pulmonary hypertension. In chronic hypoxic condition, ClCa channel may play a role in the regulation of PASMCs proliferation.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号