The inwardly rectifying K+ channel KIR7.1 controls uterine excitability throughout pregnancy.

Abnormal uterine activity in pregnancy causes a range of important clinical disorders, including preterm birth, dysfunctional labour and post-partum haemorrhage. Uterine contractile patterns are controlled by the generation of complex electrical signals at the myometrial smooth muscle plasma membrane. To identify novel targets to treat conditions associated with uterine dysfunction, we undertook a genome-wide screen of potassium channels that are enriched in myometrial smooth muscle.

Long-term channel block is required to inhibit cellular transformation by human ether-à-go-go-related gene (hERG1) potassium channels.

Both human ether-à-go-go-related gene (hERG1) and the closely related human ether-à-go-go (hEAG1) channel are aberrantly expressed in a large proportion of human cancers. In the present study, we demonstrate that transfection of hERG1 into mouse fibroblasts is sufficient to induce many features characteristic of malignant transformation. An important finding of this work is that this transformation could be reversed by chronic incubation (for 2-3 weeks) with the hERG channel blocker dofetilide (100 nM), whereas more acute applications (for 1-2 days) were ineffective.

Population patch-clamp electrophysiology analysis of recombinant GABAA alpha1beta3gamma2 channels expressed in HEK-293 cells.

Gamma-amino butyric acid (GABA)-activated Cl- channels are critical mediators of inhibitory postsynaptic potentials in the CNS. To date, rational design efforts to identify potent and selective GABA(A) subtype ligands have been hampered by the absence of suitable high-throughput screening approaches. The authors describe 384-well population patch-clamp (PPC) planar array electrophysiology methods for the study of GABA(A) receptor pharmacology.

Selective activation of the SK1 subtype of human small-conductance Ca2+-activated K+ channels by 4-(2-methoxyphenylcarbamoyloxymethyl)-piperidine-1-carboxylic acid tert-butyl ester (GW542573X) is dependent on serine 293 in the S5 segment.

A new small molecule, 4-(2-methoxy-phenylcarbamoyloxymethyl)-piperidine-1-carboxylic acid tert-butyl ester (GW542573X), is presented as an activator of small-conductance Ca(2+)-activated K(+) (SK, K(Ca)2) channels and distinguished from previously published positive modulators of SK channels, such as 1-ethyl-2-benzimidazolinone (1-EBIO) and cyclohexyl-[2-(3,5-dimethylpyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA), in several aspects. GW542573X is the first SK1-selective compound described: an EC(50) value of 8.2 +/- 0.

Use of planar array electrophysiology for the development of robust ion channel cell lines.

The tractability of ion channels as drug targets has been significantly improved by the advent of planar array electrophysiology platforms which have dramatically increased the capacity for electrophysiological profiling of lead series compounds. However, the data quality and through-put obtained with these platforms is critically dependent on the robustness of the expression reagent being used. The generation of high quality, recombinant cell lines is therefore a key step in the early phase of ion channel drug discovery and this can present significant challenges due to the diversity and organisational complexity of many channel types.

Improved functional expression of recombinant human ether-a-go-go (hERG) K+ channels by cultivation at reduced temperature.

Background: HERG potassium channel blockade is the major cause for drug-induced long QT syndrome, which sometimes cause cardiac disrhythmias and sudden death. There is a strong interest in the pharmaceutical industry to develop high quality medium to high-throughput assays for detecting compounds with potential cardiac liability at the earliest stages of drug development. Cultivation of cells at lower temperature has been used to improve the folding and membrane localization of trafficking defective hERG mutant proteins.

Population patch clamp electrophysiology: a breakthrough technology for ion channel screening.

Population patch clamp (PPC) is a novel high throughput planar array electrophysiology technique that allows ionic currents to be recorded from populations of cells under voltage clamp. For the drug discovery pharmacologist, PPC promises greater speed and precision than existing methods for screening compounds at voltage-gated ion channel targets. Moreover, certain constitutively active or slow-ligand gated channels that have hitherto proved challenging to screen with planar array electrophysiology (e.

Novel 384-well population patch clamp electrophysiology assays for Ca2+-activated K+ channels.

Planar array electrophysiology techniques were applied to assays for modulators of recombinant hIK and hSK3 Ca2+-activated K+ channels. In CHO-hIK-expressing cells, under asymmetric K+ gradients, small-molecule channel activators evoked time- and voltage-independent currents characteristic of those previously described by classical patch clamp electrophysiology methods. In single-hole (cell) experiments, the large cell-to-cell heterogeneity in channel expression rendered it difficult to generate activator concentration-response curves.

Activation of SK channels inhibits epileptiform bursting in hippocampal CA3 neurons.

The role of calcium-activated potassium channels in the regulation of neuronal hyperexcitability, as in epilepsy, is unclear. To examine this issue, we have used the acute hippocampal slice model of epileptiform activity to investigate the effects of an enhancer of SK channel activity, 1-ethyl-benzimidazolinone (EBIO). That EBIO is an SK channel modulator was confirmed by its potentiation of hSK1, hSK2, hSK3 and hIK currents (EC(50) values in the range of 130-870 microM) and its apamin (1 microM) sensitive reduction of the number of action potentials fired in CA3 pyramidal neurons in response to a depolarizing current step.

A functional role for small-conductance calcium-activated potassium channels in sensory pathways including nociceptive processes.

We investigated the role of small-conductance calcium-activated potassium (SK) and intermediate-conductance calcium-activated potassium channels in modulating sensory transmission from peripheral afferents into the rat spinal cord. Subunit-specific antibodies reveal high levels of SK3 immunoreactivity in laminas I, II, and III of the spinal cord. Among dorsal root ganglion neurons, both peripherin-positive (C-type) and peripherin-negative (A-type) cells show intense SK3 immunoreactivity.

Small and intermediate conductance Ca(2+)-activated K+ channels confer distinctive patterns of distribution in human tissues and differential cellular localisation in the colon and corpus cavernosum.

The SK/IK family of small and intermediate conductance calcium-activated potassium channels contains four members, SK1, SK2, SK3 and IK1, and is important for the regulation of a variety of neuronal and non-neuronal functions. In this study we have analysed the distribution of these channels in human tissues and their cellular localisation in samples of colon and corpus cavernosum. SK1 mRNA was detected almost exclusively in neuronal tissues.

Heterologous expression and functional analysis of rat Nav1.8 (SNS) voltage-gated sodium channels in the dorsal root ganglion neuroblastoma cell line ND7-23.

The voltage-gated sodium channel NaV1.8 (SNS, PN3) is thought to be a molecular correlate of the dorsal root ganglion (DRG) tetrodotoxin resistant (TTX-R) Na+ current. TTX-R/NaV1.

Ionworks HT: a new high-throughput electrophysiology measurement platform.

To address the throughput restrictions of classical patch clamp electrophysiology, Essen Instruments has developed a plate-based electrophysiology measurement platform. The instrument is an integrated platform that consists of computer-controlled fluid handling, recording electronics, and processing tools capable of voltage clamp whole-cell recordings from thousands of individual cells per day. To establish a recording, the system uses a planar, multiwell substrate (a PatchPlate).