Search results for "patch-clamp"
showing 10 items of 85 documents
Effect of depolarizing GABAA-mediated membrane responses on excitability of Cajal-Retzius cells in the immature rat neocortex
2011
In immature neurons activation of ionotropic GABA receptors induces depolarizing membrane responses due to a high intracellular Cl− concentration ([Cl−]i). However, it is difficult to draw conclusions about the functional consequences of subthreshold GABAergic depolarizations, since GABAergic membrane shunting and additional effects on voltage-dependent ion channels or action potential threshold must be considered. To systematically investigate factors that determine the GABAergic effect on neuronal excitability we performed whole cell patch-clamp recordings from Cajal-Retzius cells in immature rat neocortex, using [Cl−]i between 10 and 50 mM. The effect of focal GABA application was quant…
Perlecan is critical for heart stability
2008
Aims Perlecan is a heparansulfate proteoglycan found in basement membranes, cartilage, and several mesenchymal tissues that form during development, tumour growth, and tissue repair. Loss-of-function mutations in the perlecan gene in mice are associated with embryonic lethality caused primarily by cardiac abnormalities probably due to hemopericards. The aim of the present study was to investigate the mechanism underlying the early embryonic lethality and the pathophysiological relevance of perlecan for heart function. Methods and results Perlecan-deficient murine embryonic stem cells were used to investigate the myofibrillar network and the electrophysiological properties of single cardiomy…
Nitric oxide and excitatory postsynaptic currents in immature rat sympathetic preganglionic neurons in vitro.
1997
Neuronal nitric oxide synthase immunoreactivity was localized to sympathetic preganglionic neurons of the intermediolateral cell column and cyclic GMP immunoreactivity to nerve fibers projecting into the intermediolateral cell column of 20-25-day-old rats. Whole-cell patch-clamp recordings were made from sympathetic preganglionic neurons in spinal cord slices of immature rats and the role of nitric oxide and cyclic GMP on excitatory postsynaptic currents was studied. Superfusing the slices with the nitric oxide precursor L-arginine (300 microM) increased the amplitude of evoked excitatory postsynaptic currents as well as the frequency of spontaneous miniature excitatory postsynaptic current…
GABAergic projections from the subplate to Cajal-Retzius cells in the neocortex.
2011
Subplate neurons and Cajal-Retzius cells play an important role in the corticogenesis. Despite morphological evidence, the question whether subplate neurons innervate Cajal-Retzius cells has not been studied yet. We report that electrical stimulation in the subplate resulted in evoked GABAergic inhibitory postsynaptic currents (eIPSCs) in Cajal-Retzius cells. The eIPSC latency showed minor variability and amounted to approximately 4 ms, suggesting the monosynaptic connection. During the first postnatal week: (i) eIPSC amplitude increased, (ii) eIPSC kinetics sped up, (iii) the size of readily releasable pool increased, and (iv) γ-aminobutyric acid release probability decreased. We conclude …
Modulation of voltage-gated K(+) channels Kv11 and Kv1 4 by forskolin.
2002
Forskolin (FSK) affects voltage-gated K + (Kv) currents in different cell types, but it is not known which of the various subunits form FSK-sensitive Kv channels. We compared the effect of the compound at Kv1.1 and Kv1.4 channels ectopically expressed in HEK 293 cells. Low FSK concentrations induced a phosphorylation-dependent potentiation of Kv1.1 currents. At higher concentrations, this effect was superimposed by a fast, cAMP-independent channel block. Kv1.4 currents were inhibited with lower potency by FSK but were not modified by phosphorylation. The variable effect of the compound might help to distinguish between Kv subunits expressed by native cells. 2002 Elsevier Science Ltd. All …
Analysis of phosphorylation-dependent modulation of Kv1.1 potassium channels.
2003
The voltage-gated potassium channel Kv1.1 contains phosphorylation sites for protein kinase A (PKA) and protein kinase C (PKC). To study Kv1.1 protein expression and cellular distribution in regard to its level of phosphorylation, the effects of PKA and PKC activation on Kv1.1 were investigated in HEK 293 cells stably transfected with Kv1.1 (HEK 293/1). Without kinase activation, HEK 293/1 cells carry unphosphorylated Kv1.1 protein in the plasma membranes, whereas large amounts of phosphorylated and unphosphorylated Kv1.1 protein were located intracellularly. Activation of PKA resulted in phosphorylation of intracellular Kv1.1 protein, followed by a rapid translocation of Kv1.1 into the pla…
Glycine Receptors Mediate Excitation of Subplate Neurons in Neonatal Rat Cerebral Cortex
2008
The development of the cerebral cortex depends on genetic factors and early electrical activity patterns that form immature neuronal networks. Subplate neurons (SPn) are involved in the construction of thalamocortical innervation, generation of oscillatory network activity, and in the proper formation of the cortical columnar architecture. Because glycine receptors play an important role during early corticogenesis, we analyzed the functional consequences of glycine receptor activation in visually identified SPn in neocortical slices from postnatal day 0 (P0) to P4 rats using whole cell and perforated patch-clamp recordings. In all SPn the glycinergic agonists glycine, β-alanine, and taurin…
Pathway-specificity in N-methyl-d-aspartate receptor-mediated synaptic inputs onto subplate neurons
2007
The subplate plays an important role in forming neuronal connections during early cortical development. We characterized by the use of whole-cell and cell-attached patch-clamp recordings in coronal brain slices from newborn mice (postnatal day [P] 0-3) the functional properties of two major pathways onto subplate neurons (SPn), the thalamocortical and the intra-subplate synaptic input. The two afferent pathways were stimulated extracellularly with bipolar electrodes placed in the thalamus and the subplate, respectively. Synaptically evoked and pharmacologically isolated N-methyl-d-aspartate receptor (NMDAR) -mediated responses with an onset latency of approximately 6 ms could be reliably re…
Activation by Acidic pH of CLC-7 Expressed in Oocytes from Xenopus laevis
2002
ClC chloride channels are important in diverse physiological functions such as transepithelial transport, cell volume regulation, excitability, and acidification of intracellular organelles. We have investigated the expression of CLC-7 in oocytes from Xenopus laevis with the two electrode voltage clamp technique and Western blot analysis. Using a specific antibody against CLC-7, we found an approximately 80 kDa protein in oocytes, previously injected with CLC-7-cRNA. In voltage clamp experiments on ClC-7-cRNA-injected oocytes, no current changes were detected at normal pH (7.4). However, acidification of the Ringer solution to pH values between 6 and 4 revealed strong currents which reverse…
Intracellular accumulation of l-Arg, kinetics of transport, and potassium leak conductance in oocytes from Xenopus laevis expressing hCAT-1, hCAT-2A,…
2004
AbstractCationic amino acid transporters play an important role in the intracellular supply of l-Arg and the generation of nitric oxide. Since the transport of l-Arg is voltage-dependent, we aimed at determining the intracellular l-Arg concentration and describing the transport of l-Arg in terms of Michaelis–Menten kinetics, taking into account membrane voltage. The human isoforms of the cationic amino acid transporters, hCAT-1, hCAT-2A, and hCAT-2B, were expressed in oocytes from Xenopus laevis and studied with the voltage clamp technique and in tracer experiments. We found that l-Arg was concentrated intracellularly by all hCAT isoforms and that influx and efflux, in the steady state of e…