Membrane voltage, resistance, and channel switching in isolated mouse fibroblasts (L cells): a patch‐electrode analysis.

Hosoi, Shigeru; Slayman, Clifford L.

doi:10.1113/jphysiol.1985.sp015824

Cited by 30 publications

(25 citation statements)

References 55 publications

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“…The high membrane resistance of 4·1 ± 0·1 GÙ measured in human atrial fibroblasts corresponds to the values of membrane resistance for fibroblasts from different species (Hosoi & Slayman, 1985;Lovisolo et al 1988). Membrane resistance for cardiac fibroblasts represented in the literature ranges from 0·5 to 25 GÙ (Rook et al 1989;Kohl et al 1992Kohl et al , 1994Kondratjev et al 1993).…”

Section: Baseline Electrophysiological Propertiesmentioning

confidence: 99%

Mechanically Induced Potentials in Fibroblasts from Human Right Atrium

Kamkin

Kiseleva

Wagner

et al. 1999

Experimental Physiology

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summaryIt has been shown that cardiac fibroblasts of the human heart are electrically non-excitable and mechanosensitive. The resting membrane potential of these cells is −15·9 ± 2·1 mV and the membrane resistance is 4·1 ± 0·1 GÙ. Rhythmic contractions of the myocardium associated with stretch of the surrounding tissue produce reversible changes in the membrane potential of cardiac fibroblasts. These mechanically induced potentials (MIPs) follow the rhythm of myocardial contractions. Simultaneous recording of the action potential of cardiomyocytes and MIPs of cardiac fibroblasts demonstrates a delay of 40·0 ± 0·4 ms after the action potential before the appearance of the MIP. Contraction produces a MIP which is more positive or more negative than the reversal potential -the membrane potential due to current injection at which the MIP reverses its direction. Regardless of the initial orientation of the MIP, intracellular polarization increases the amplitude towards the reversal potential if the background MIP had depolarized the membrane or away from the reversal potential if the initial background MIP had hyperpolarized the membrane. Artificial intracellular polarization changed the amplitude but not the frequency of the MIP.

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Section: Baseline Electrophysiological Propertiesmentioning

confidence: 99%

Mechanically Induced Potentials in Fibroblasts from Human Right Atrium

Kamkin

Kiseleva

Wagner

et al. 1999

Experimental Physiology

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“…One possibility could be that all cells express 'K+ leak' whose activity depends on a diffusible factor which dialyses away in whole cell but does not pass through gap junctions. A patchclamp study in mouse L cells (Hosoi & Slayman, 1985) suggested that the resting membrane conductance is K+ dominated which decayed over a period of minutes. An interesting hypothesis to consider, however, is the possibility that the establishment of open gap junctions between cells causes the formation of voltage-independent K+ channels.…”

Section: Voltage-independent Channelsmentioning

confidence: 99%

Characterization of ion channels seen in subconfluent human dermal fibroblasts.

Estacion¹

1991

The Journal of Physiology

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SUMMARY1. Ion channels expressed in human dermal fibroblasts are characterized using the patch-clamp technique.2. A number of different ion channels were found but their expression occurred at various frequencies. The most commonly found phenotype was the expression of voltage-gated K+ current. This 'typical' K+ current was seen in about 60% of the cells recorded.3. Subtypes of voltage-gated K+ channels could be discerned by differences in gating kinetics. One has fast inactivation and resembles the 'A' K+ current. Additional subtypes were sometimes discerned based on activation kinetics.4. The large-conductance Ca2+-activated K+ channel (maxi-K+) could be found in nearly every cell but required large depolarizations to activate using the standard Ca2l-buffered pipette solution (10-8 M [Ca2+]i).5. Inward rectifier K+ channels were seen in a low percentage of cells. The inward rectifier K+ current was sensitive to 'wash-out' if guanosine 5'-O-(3-thiotriphosphate) (GTPyS) was included in the pipette solution dialysing the cell.6. Tetrodotoxin (TTX)-sensitive voltage-gated Na+ channels were seen but in a lower number of cells recorded, about 20 %. Evidence for subtypes of Na+ channels were sometimes seen based on differences in gating kinetics.7. An ATP-dependent osmotically activated Cl-current was also found. This current showed some outward rectification but was otherwise voltage independent.8. In addition, a cell-to-cell contact-associated K+ current was described. This current was linear over the voltage ranges used and whose gating correlated with the existence of gap junctions.9. These currents were characterized to determine the baseline behaviour of unstimulated cells and to compare to bradykinin-stimulated cells described in the following paper. As unexcitable cells, human dermal fibroblasts are capable of expressing a surprising diversity of ion channel phenotypes and of ion channel modulations.

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“…Taken together, these results are in accord with the concept that the protein encoded in WS3-10 mRNA leads to an alteration in one or more intracellular Ca2+-dependent processes during HDF senescence. Ca2+ flux activates several physiologic functions in nonexcitable cells, including gene expression, initiation of DNA synthesis, entry into mitosis, and cell contractility and motility (1)(2)(3)(4)(5)(6)(7). Although we used a standard pipet solution (Ca2+ at 110 nM) to dialyze the interior ofthe cell, membrane currents were measured within 1.5 min after rupture ofthe membrane, before [Ca2+]i of HDFs has been quantified by others under a variety of conditions.…”

Section: Discussionmentioning

confidence: 99%

“…However, slope conductances of senescent and WS cells measured in response to 20-mV hyperpolarizing pulses from the holding potential of -40 mV were 35% and 23%, respectively, of those in control young HDFs ( perhaps to "age" heterogeneity, due to the admixture of senescent cells that exists among young cells in mass cultures (11,12). Internal dialysis of WS HDFs with pipet solutions containing 5 Translation of WS3-10 mRNA in Vitro. To confirm that the WS3-10 gene sequence does in fact express a protein, we translated WS3-10 mRNA in a rabbit reticulocyte lysate (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…activates K+ channels, the major components of membrane conductance (4)(5)(6)(7). We recently isolated a gene sequence, WS3-10, which was overexpressed in a cDNA library derived from mRNA of prematurely senescent human diploid fibroblasts (HDFs) from apatient with Werner syndrome (WS), and accordingly, the levels of mRNA cognate to WS3-10 were shown to be higher in both WS and senescent HDFs than in young HDFs (8,9).…”

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confidence: 99%

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