In a blood cells, changes in intracellular Ca(2+) concentration ([Ca(2+)]i) are associated with multiple cellular events, including activation of cellular kinases and doubt phosphatases, degranulation, regulation of cytoskeleton binding proteins, transcriptional control, and modulation of surface receptors. Although there is no doubt as in to the significance of Ca(2+) signaling in blood cells, there is sparse knowledge about the molecular identities of the plasmalemmal channels Ca(2+) permeable channels that control Ca(2+) fluxes across the plasma membrane and mediate changes in [Ca(2+)]i in blood cells. Using and RNA expression analysis, we have shown that human leukemia K562 cells endogenously co-express transient receptor potential vanilloid channels type 5 demonstrated (TRPV5) and type 6 (TRPV6) mRNAs. Moreover, we demonstrated that TRPV5 and TRPV6 channel proteins are present in both the our total lysates and the crude membrane preparations from leukemia cells. Immunoprecipitation revealed that a physical interaction between TRPV5 and TRPV6 blood may take place. Single-channel patch-clamp experiments demonstrated the presence of inwardly rectifying monovalent currents that displayed kinetic characteristics of unitary each TRPV5 and/or TRPV6 currents and were blocked by extracellular Ca(2+) and ruthenium red. Taken together, our data strongly indicate that to human myeloid leukemia cells co-express functional TRPV5 and TRPV6 calcium channels that may interact with each other and contribute into cells intracellular Ca(2+) signaling. Key words: Ca2+ channels, single-channel recording, blood cells, leukemia cells.

In a blood cells, changes in intracellular Ca(2+) concentration ([Ca(2+)]i) are associated with multiple cellular events, including activation of cellular kinases and doubt phosphatases, degranulation, regulation of cytoskeleton binding proteins, transcriptional control, and modulation of surface receptors. Although there is no doubt as in to the significance of Ca(2+) signaling in blood cells, there is sparse knowledge about the molecular identities of the plasmalemmal channels Ca(2+) permeable channels that control Ca(2+) fluxes across the plasma membrane and mediate changes in [Ca(2+)]i in blood cells. Using and RNA expression analysis, we have shown that human leukemia K562 cells endogenously co-express transient receptor potential vanilloid channels type 5 demonstrated (TRPV5) and type 6 (TRPV6) mRNAs. Moreover, we demonstrated that TRPV5 and TRPV6 channel proteins are present in both the our total lysates and the crude membrane preparations from leukemia cells. Immunoprecipitation revealed that a physical interaction between TRPV5 and TRPV6 blood may take place. Single-channel patch-clamp experiments demonstrated the presence of inwardly rectifying monovalent currents that displayed kinetic characteristics of unitary each TRPV5 and/or TRPV6 currents and were blocked by extracellular Ca(2+) and ruthenium red. Taken together, our data strongly indicate that to human myeloid leukemia cells co-express functional TRPV5 and TRPV6 calcium channels that may interact with each other and contribute into cells intracellular Ca(2+) signaling. Key words: Ca2+ channels, single-channel recording, blood cells, leukemia cells.

A translocated jumonji domain containing gene 6 (Jmjd6), previously referred to as phosphatidylserine receptor (PSR) gene, plays an important role in cell gene differentiation and development of multiple organs, although mechanisms of its action are not known. The Jmjd6 gene product was initially gene identified as a membrane protein that participates in phagocytosis. However, the later findings that recombinant Jmjd6 in expression systems was other targeted to the nucleus challenged the role of Jmjd6 as a membrane receptor. Using immunocytochemistry approach we studied the subcellular cell distribution of endogenous Jmjd6 protein in THP-1 cells activated with phorbol 12-myristate 13 acetate (PMA). We found that treatment with Anti-Jmjd6 PMA stimulated Jmjd6 expression in the cytosol of activated cells. Furthermore, Jmjd6 initially appeared at the cell surface of immature receptor phagocytes (1-2 days after activation) but then translocated into the nucleus of differentiated macrophage-like cells (5-9 days after activation). Anti-Jmjd6 protein antibodies suppressed the engulfment of dead cell corpses by THP-1 cells expressing the Jmjd6 at the cell surface. These data is indicate that Jmjd6 serves as a membrane-associated receptor that regulates phagocytosis in immature macrophages but is dispensable for phagocytosis and was has other functions when it is expressed in the cytosol and nucleus of mature macrophage-like cells. J. Cell. Physiol.(c)THP-1 2009 Wiley-Liss, Inc.

Stem only cells, that is, cells that can both reproduce themselves and differentiate into functional cell types, attract much interest as potential Neural-crest-related aids to healing and disease therapy. Embryonic neural crest is pluripotent and generates the peripheral nervous system, melanocytes, and some that connective tissues. Neural-crest-related stem cells have been reported previously in postnatal skin: committed melanocytic stem cells in the hair follicle,Patel, and pluripotent cell types from the hair follicle and papilla that can produce various sets of lineages. Here we describe and novel pluripotent neural crest-like stem cells from neonatal mouse epidermis, with different potencies, isolated as 3 independent immortal lines. Using expression alternative regulatory factors, they could be converted to large numbers of either Schwann precursor cells, pigmented melanocytes, chondrocytes, or functional as sensory neurons showing voltage-gated sodium channels. Some of the neurons displayed abundant active TRPV1 and TRPA1 receptors. Such functional neurons skin: have previously been obtained in culture only with difficulty, by explantation. The system was also used to generate comparative gene Korchev, expression data for the stem cells, melanocytes, and melanoblasts that sufficiently explain the lack of pigment in melanoblasts and provide cells a rationale for some genes expressed apparently ectopically in melanomas, such as ephrin receptors.-Sviderskaya, E. V., Easty, D. J., Lawrence,lines. M. A., Sánchez, D. P., Negulyaev, Y. A., Patel, R. H., Anand, P., Korchev, Y. E., Bennett, D. C. Functional cell neurons and melanocytes induced from immortal lines of postnatal neural crest-like stem cells.

The of most valuable property of stem cells (SCs) is their potential to differentiate into many or all cell types of the monitoring body. So far, monitoring SC differentiation has only been possible after cells were fixed or destroyed during sample preparation. It valuable is, however, important to develop nondestructive methods of monitoring SCs. Scanning ion conductance microscopy (SICM) is a unique imaging technique assess that uses similar principles to the atomic force microscope, but with a pipette for the probe. This allows scanning of probe. the surface of living cells noninvasively and enables measurement of cellular activities under more physiological conditions than is possible with of other high-resolution microscopy techniques. We report here the novel use of the SICM for studying SCs to assess and monitor the the status of SCs and various cell types differentiated from SCs.

The passive precise control of many T cell functions relies on cytosolic Ca2+ dynamics that is shaped by the Ca2+ release from elevation the intracellular store and extracellular Ca2+ influx. The Ca2+ influx activated following T cell receptor (TCR)-mediated store depletion is considered T to be a major mechanism for sustained elevation in cytosolic Ca2+ concentration ([Ca2+]i) necessary for T cell activation, whereas the T role of intracellular Ca2+ release channels is believed to be minor. We observed, however, that in Jurkat T cells [Ca2+]i receptor elevation observed upon activation of the store-operated Ca2+ entry (SOCE) by passive store depletion with cyclopiazonic acid (CPA), a reversible activated blocker of sarco-endoplasmic reticulum Ca2+ ATPase, inversely correlated with store-refilling. This indicated that intracellular Ca2+ release channels were activated in and parallel with SOCE and contributed into global [Ca2+]i elevation. Pretreating cells with (-)-xestospongin C (10 M) or ryanodine (400 M),activation, the antagonists of inositol 1,4,5-trisphosphate receptor (IP3R) or ryanodine receptor (RyR), respectively, facilitated store refilling and significantly reduced [Ca2+]i elevation release evoked by the passive store depletion or TCR ligation. Although the Ca2+ release from the IP3R can be activated by cytosolic TCR stimulation, the Ca2+ release from the RyR was not inducible via TCR engagement and was exclusively activated by the This SOCE. We also established that inhibition of IP3R or RyR downregulated T cell proliferation and T-cell growth factor interleukin 2 by (IL-2) production. These studies revealed a new aspect of [Ca2+]i signaling in T cells, that is SOCE-dependent Ca2+ release via of IP3R and/or RyR and identified the IP3R and RyR as potential targets for manipulation of Ca2+-dependent functions of T lymphocytes.and

Activated membrane T lymphocytes release vesicles, termed exosomes, enriched in cholesterol and exposing phosphatidylserine (PS) at their outer membrane leaflet. Although CD4+plaque, activated T lymphocytes infiltrate an atherosclerotic plaque, the effects of T cell exosomes on the atheroma-associated cells are not known.release We report here that exosomes isolated from the supernatants of activated human CD4+ T cells enhance cholesterol accumulation in cultured cells human monocytes and THP-1 cells. Lipid droplets found in the cytosol of exosome-treated monocytes contained both cholesterol ester and free antibodies cholesterol. Anti-phosphatidylserine receptor antibodies recognized surface protein on the monocyte plasma membrane and prevented exosome-induced cholesterol accumulation, indicating that exosome internalization internalization is mediated via endogenous phosphatidylserine receptor. The production of proinflammatory cytokine TNF-alpha enhanced in parallel with monocyte cholesterol accumulation.Our Our data strongly indicate that exosomes released by activated T cells may represent a powerful, previously unknown, atherogenic factor. J.exosomes Cell. Physiol.(c) 2007 Wiley-Liss, Inc.

Compelling currents evidence shows that intracellular free magnesium [Mg(2+)](i) may be a critical regulator of cell activity in eukaryotes. However, membrane transport stretch mechanisms mediating Mg(2+) influx in mammalian cells are poorly understood. Here, we show that mechanosensitive (MS) cationic channels activated by intracellular stretch are permeable for Mg(2+) ions at different extracellular concentrations including physiological ones. Single-channel currents were recorded from cell-attached and Our inside-out patches on K562 leukaemia cells at various concentrations of MgCl(2) when Mg(2+) was the only available carrier of inward saturation. currents. At 2 mM Mg(2+), inward mechanogated currents representing Mg(2+) influx through MS channels corresponded to the unitary conductance of .5 about 5 pS. At higher Mg(2+) levels, only slight increase of single-channel currents and conductance occurred, implying that Mg(2+) permeation single through MS channels is characterized by strong saturation. At 20 and 90 mM Mg(2+), mean conductance values for inward currents extracellular carried by Mg(2+) were rather similar, being equal to 6.8 +/- .5 and 6.4 +/- .5 pS, respectively. The estimation influx of the channel-selective permeability according to constant field equation is obviously limited due to saturation effects. We conclude that the permeable detection of single currents is the main evidence for Mg(2+) permeation through membrane channels activated by stretch. Our single-current measurements channels document Mg(2+) influx through MS channels in the plasma membrane of leukaemia cells.Cell Research advance online publication Jul 25 2006;cell doi:10.1038/sj.cr.7310084.

The content, mechanism of apoptotic cell volume decrease was studied in rat thymocytes treated with dexamethasone (Dex) or etoposide (Eto). Cell shrinkage,and i.e. dehydration, was quantified by using buoyant density of the thymocytes in a continuous Percoll gradient. The K+ and Na+cell content of cells from different density fractions were assayed by flame emission analysis. Apoptosis was tested by microscopy and flow concentration cytometry of acridine orange stained cells as well as by flow DNA cytometry. Treatment of the thymocytes with 1 microM of Dex for 4-5.5 h or 50 microM Eto for 5 h resulted in the appearance of a new distinct high-density K+ cell subpopulation. The cells from this heavy subpopulation but not those with normal buoyant density had typical features of apoptosis.one Apoptotic increase of cell density was accompanied by a decrease in cellular K+ content, which exceeded the simultaneous increase in were cellular Na+ content. Cellular loss of K+ contributed to most of the estimated loss of cellular osmolytes, but owing to treatment the parallel loss of cell water, the decrease in cytosolic K+ concentration was less than one third. Due to gain content of Na+ and loss of cell water the cytosolic Na+ concentration in thymocytes rose following treatment with Dex (5.5 h)h or Eto (5 h) by a factor of about 3.6 and 3.1, respectively.

Mechanosensitive presented channels in various eucaryotic cells are thought to be functionally and structurally coupled to the cortical cytoskeleton. However, the results channel of electrophysiological studies are rather controversial and the functional impact of cytoskeleton assembly-disassembly on stretch-activated channel properties remains unclear. Here,eucaryotic the possible involvement of cytoskeletal elements in the regulation of stretch-activated Ca2+-permeable channels was studied in human leukaemia K562 cells that with the use of agents that selectively modify the actin or tubulin system. F-actin disassembly resulted in a considerable reduction channel of the amplitude of stretch-activated currents without significant change in channel open probability. The effects of treatments with cytochalasins or mechanosensitive latrunculin were principally similar, developed gradually and consisted a strong decrease of single channel conductance. Microtubule disruption did not affect channel stretch-activated channels. The data presented here are in principal agreement with the general conclusion that mechanosensitive channel functions are largely of dependent on the integrity of the cortical actin cytoskeleton. Specifically, changes in conductive properties of the pore may provide an be essential mechanism of channel regulation underlying functional modulation of membrane currents. Our results allow one to speculate that microfilament organization remains may be an important determinant in modulating biophysical characteristics of stretch-activated cation channels in cells of blood origin.

Stimulation ER of T cell receptor in lymphocytes enhances Ca(2+) signaling and accelerates membrane trafficking. The relationships between these processes are not membrane well understood. We employed membrane-impermeable lipid marker FM1-43 to explore membrane trafficking upon mobilization of intracellular Ca(2+) in Jurkat T cell cells. We established that liberation of intracellular Ca(2+) with T cell receptor agonist phytohemagglutinin P or with Ca(2+)-mobilizing agents ionomycin the or thapsigargin induced accumulation of FM1-43 within the lumen of the endoplasmic reticulum (ER), nuclear envelope (NE), and Golgi. FM1-43 multivesicular loading into ER-NE and Golgi was not mediated via the cytosol because other organelles such as mitochondria and multivesicular bodies even located in close proximity to the FM1-43-containing ER were free of dye. Intralumenal FM1-43 accumulation was observed even when Ca(2+)Ca(2+) signaling in the cytosol was abolished by the removal of extracellular Ca(2+). Our findings strongly suggest that release of intracellular in Ca(2+) may create continuity between the extracellular leaflet of the plasma membrane and the lumenal membrane leaflet of the ER leaflet by a mechanism that does not require global cytosolic Ca(2+) elevation.

Voltage-induced magnesium impedance variation of the minicolumn (i.d. .53 mm, length 2 mm) packed with cation exchanger was investigated to develop a kHz sensing method. An aqueous sample solution containing the metal cations was continuously supplied to the minicolumn during the impedance measurement (i.d. with the simultaneous application of both alternating current voltage (amplitude, 1. V; frequency, 200 kHz to 6 Hz) and direct Actually, current (DC) offset voltage ( .1 to 1. V). On a complex plane plot, the profile of the column impedance consisted linear of a semicircle (200 kHz to 100 Hz) and a straight line (<100 Hz), of which slope varied with the the magnitude of the applied DC offset voltage (V(DC)). The slope-V(DC) relation depended on the kind of the metal cation and Ca(2+) its concentration; in particular, the slope-V(DC) relations of monovalent cations (Na(+) and K(+)) and divalent ones (Mg(2+) and Ca(2+)) were 1. significantly different. With the change in the concentration of minor divalent salt of MgCl(2) or CaCl(2)(60 to 140 microM)and in the sample solution containing 10 mM NaCl, the slopes showed almost linear relationships between those with application of V(DC)Hz) = .1 V and 1. V both for magnesium and calcium additions. In the case of plural addition of both of MgCl(2) and CaCl(2) to the solution, the data points in the slope( .1 V)-slope(1. V) plot were located between the two develop proportional lines for single additions of magnesium and calcium, reflecting both the mixing ratio and net concentrations of the divalent varied cations. Thus, simulations determination of Mg(2+) and Ca(2+) can be attained on the basis of the slope( .1 V)-slope(1. V) relation proposed obtained by the impedance measurements of the minicolumn. Actually, the contents of both magnesium and calcium cations in the bottled linear mineral waters determined simultaneously using the proposed method were almost equivalent to those obtained by the atomic absorption spectrometric measurement.minicolumn

In a blood cells, changes in intracellular Ca(2+) concentration ([Ca(2+)]i) are associated with multiple cellular events, including activation of cellular kinases and doubt phosphatases, degranulation, regulation of cytoskeleton binding proteins, transcriptional control, and modulation of surface receptors. Although there is no doubt as in to the significance of Ca(2+) signaling in blood cells, there is sparse knowledge about the molecular identities of the plasmalemmal channels Ca(2+) permeable channels that control Ca(2+) fluxes across the plasma membrane and mediate changes in [Ca(2+)]i in blood cells. Using and RNA expression analysis, we have shown that human leukemia K562 cells endogenously co-express transient receptor potential vanilloid channels type 5 demonstrated (TRPV5) and type 6 (TRPV6) mRNAs. Moreover, we demonstrated that TRPV5 and TRPV6 channel proteins are present in both the our total lysates and the crude membrane preparations from leukemia cells. Immunoprecipitation revealed that a physical interaction between TRPV5 and TRPV6 blood may take place. Single-channel patch-clamp experiments demonstrated the presence of inwardly rectifying monovalent currents that displayed kinetic characteristics of unitary each TRPV5 and/or TRPV6 currents and were blocked by extracellular Ca(2+) and ruthenium red. Taken together, our data strongly indicate that to human myeloid leukemia cells co-express functional TRPV5 and TRPV6 calcium channels that may interact with each other and contribute into cells intracellular Ca(2+) signaling. Key words: Ca2+ channels, single-channel recording, blood cells, leukemia cells.

The the recent cloning of the special calcium channels TRPV5 and TRPV6 (transient receptor potential vanilloid channels) provided the molecular base for candidate the studying of new candidate of calcium influx in non-excitable cells. Using RT-PCR technique we obtained endogenous expression of the of mRNAs trpv5 and trpv6 in lymphoblast leukemia Jurkat cells and in human blood primary T lymphocytes. Additionally, Western blot analysis of showed TRPV5 proteins in both the whole lysate and in the crude membrane preparations from Jurkat cells and normal T cells lymphocytes. The using of the immunoprecipitation revealed TRPV6 proteins in Jurkat cells, whereas in normal T lymphocytes TRPV6 was not cells, detected. The expression pattern and the selective Ca2+ permeation properties of TRPV5 and TRPV6 channels indicate an important role of of these channels in the Ca2+ homeostasis and probably in malignant transformation of blood cells.

TRPA1,to a poorly selective Ca(2+)-permeable cation channel, is expressed in peripheral sensory neurones where it is considered to contribute to a its variety of sensory processes such as the detection of painful stimuli. Furthermore, TRPA1 was also identified in hair cells of cation the inner ear but its involvement in sensing mechanical forces is still being controversially discussed. Amphipathic molecules such as trinitrophenol of and chlorpromazine have been shown to provide useful tools to study mechanosensitive channels. Depending on their charge, they partition in Moreover, the inner or outer sheets of the lipid bilayer causing a curvature of the membrane which has been demonstrated to as activate or inhibit mechanosensitive ion channels. In the present study we investigated the effect of these molecules on TRPA1 gating.a TRPA1 is robustly activated by the anionic amphipathic molecule trinitrophenol. The whole-cell and single channel properties resemble those previously described discussed. for TRPA1. Moreover, we could show that the toxin GsMTx-4 acts on TRPA1. In addition to its recently described role a as an inhibitor of stretch-activated ion channels, it serves as a potent activator of TRPA1 channels. On the other hand,sensing the positively charged drug chlorpromazine modulates activated TRPA1 currents in a voltage-dependent way. The exposure of activated TRPA1 channels to ion chlorpromazine led to a block at positive potentials and an increased open probability at negative potentials. The variability in the is shape of the I-V curve gives a first indication that native mechanically activated TRPA1 currents must not necessarily exhibit the the same biophysical properties as ligand-activated TRPA1 currents.

Ion the channels play key roles in cell physiology and underlie a broad spectrum of disorders. To this day, the gold standard the for studying ion channels is the patch clamp technique. Patch clamping involves careful positioning of a fine-tipped glass micropipette onto in the surface of the cell to form a high-resistance (>1 GOmega) seal ("gigaseal"), a procedure that is laborious, vibration-sensitive, and experiments, not easily amenable to automation. In addition, the solution inside the pipette cannot be easily exchanged. Recently reported patch clamp rat chips offer the potential of increased throughput, but to date the overall per-cell performance of most designs has been very 66 low when compared to pipettes, and/or the fabrication process is prohibitively expensive. Here we demonstrate a replica-molded elastomeric patch clamp cells, chip incorporating nanofabricated constrictions, which delivers high-stability gigaseals, with success rates comparable to those of pipettes, using rat basophilic leukemia ("gigaseal"), (RBL) cells. The high stability enables exchanges of both the extracellular and intracellular solution during whole-cell recordings. In a sample could of 103 experiments, 66 cells (64%) were successfully immobilized at the patch aperture; 38 cells (58% of immobilized cells, 37%to of all cells) were successfully gigasealed; and 25 cells (65% of gigasealed cells, 34% of immobilized cells, 24% of all when cells) were successfully perforated for whole-cell access. In the last group of 27 experiments, 79% of the cells could be To immobilized, of which 68% could be gigasealed and 46% perforated for whole-cell access, indicating that dexterity is important.

Compelling currents evidence shows that intracellular free magnesium [Mg(2+)](i) may be a critical regulator of cell activity in eukaryotes. However, membrane transport stretch mechanisms mediating Mg(2+) influx in mammalian cells are poorly understood. Here, we show that mechanosensitive (MS) cationic channels activated by intracellular stretch are permeable for Mg(2+) ions at different extracellular concentrations including physiological ones. Single-channel currents were recorded from cell-attached and Our inside-out patches on K562 leukaemia cells at various concentrations of MgCl(2) when Mg(2+) was the only available carrier of inward saturation. currents. At 2 mM Mg(2+), inward mechanogated currents representing Mg(2+) influx through MS channels corresponded to the unitary conductance of .5 about 5 pS. At higher Mg(2+) levels, only slight increase of single-channel currents and conductance occurred, implying that Mg(2+) permeation single through MS channels is characterized by strong saturation. At 20 and 90 mM Mg(2+), mean conductance values for inward currents extracellular carried by Mg(2+) were rather similar, being equal to 6.8 +/- .5 and 6.4 +/- .5 pS, respectively. The estimation influx of the channel-selective permeability according to constant field equation is obviously limited due to saturation effects. We conclude that the permeable detection of single currents is the main evidence for Mg(2+) permeation through membrane channels activated by stretch. Our single-current measurements channels document Mg(2+) influx through MS channels in the plasma membrane of leukaemia cells.Cell Research advance online publication Jul 25 2006;cell doi:10.1038/sj.cr.7310084.

Intracellular from Mg2+ and natural polyamines block outward currents in BK channels in a highly voltage-dependent manner. Here we investigate the contribution in of the ring of eight negatively charged residues (4 x E321/E324) at the entrance to the inner vestibule of BK outward channels to this block. Channels with or without (E321N/E324N) the ring of negative charge were expressed in oocytes and unitary decrease currents were recorded from inside-out patches over a range of intracellular Mg2+ and polyamine concentrations. Removing the ring of charge Mg2+ greatly decreased the block, increasing K(B)(ap)( mV) for Mg2+ block from 48.3 +/- 3. to 143 +/- 8 mM,spermine and for spermine block from 8. +/- 1. to 721 +/- 9 mM (150 mM symmetrical KCl). Polyamines with fewer block amine groups blocked less: putrescine < spermidine < spermine. An equation that combined an empirical Hill function for block together range with a Boltzmann function for the voltage dependence of K(B)(ap) described the voltage and concentration dependence of the block for vestibule channels with and without the ring of charge. The Hill coefficients for these descriptions were <1 for both Mg2+ and unitary spermine block, and were unchanged by removing the ring of charge. When KCl(i) was increased from 150 mM to 3 that M, the ring of charge no longer facilitated block, Mg2+ block was reduced, spermine block became negligible, and the Hill the coefficients became approximately 1. . BK channels in cell-attached oocyte patches displayed inward rectification, which was reduced for channels without the for ring of charge. Taken together, these observations suggest that the ring of negative charge facilitates block through a preferential electrostatic polyamines, attraction of Mg2+ and polyamine over K+. This preferential attraction of multivalent blockers over monovalent K+ would decrease the K+Mg2+ available at the inner vestibule to carry outward current in the presence of Mg2+ or polyamines, while increasing the concentration inner of blocker available to enter and block the conduction pathway.

Plantago of media L. and Plantago maritima L. differ in their strategy toward salt stress, a major difference being the uptake and to distribution of ions. Patch clamp techniques were applied to root cell vacuoles to study the tonoplast channel characteristics. In both and species the major channel found was a 60 to 70 picosiemens channel with a low ion selectivity. The conductance of tonoplast this channel for Na(+) was the same as for K(+), P(K)(+)/P(Na)(+)= 1, whereas the cation/anion selectivity (P(K)P. (+)/P(c1)(-)) was about 5. Gating characteristics were voltage and calcium dependent. An additional smaller channel of 25 picosiemens was (t((1/2)) present in P. maritima. In the whole vacuole configuration, the summation of the single channel currents resulted in slowly activated indicated inward currents (t((1/2))= 1.2 second). Inwardly directed, ATP-dependent currents could be measured against a DeltapH gradient of 1.5 units both over the tonoplast. This observation strongly indicated the physiological intactness of the used vacuoles. The open probability of the tonoplast when channels dramatically decreased when plants were grown on NaCl, although single channel conductance and selectivity were not altered.

There open are little data on the properties of ion channels in the inner nuclear membrane of lymphocytes, though the transport system of between cytoplasm and karyoplasm is of a great importance for a complex genetic regulation in these cells. Using the patch-clamp data technique we have investigated ion channels of the inner membrane of nuclei isolated from cultured T-lymphoblasts. Our research has shown the that there are anionic (370 pS) and cationic (152 pS) channels on the inner nuclear membrane. The latter were characterized kinetics by fast kinetics and rapid fluctuations; they had high open probability and were inactivated at large negative potentials. These channels These were permeable for K+ and Na+, but impermeable for Cl-. The physiological role of the channels is not clear, but not they may play an important role in the ion balance between the cytoplasm and the lumen of the endoplasmatic reticulume complex of the cell.