Contribution of two types of calcium currents to the pacemaker potentials of rabbit sino‐atrial node cells.

Hagiwara, Nobuhisa; Irisawa, Hiroshi; Kameyama, Masaki

doi:10.1113/jphysiol.1988.sp016916

Cited by 745 publications

(573 citation statements)

References 34 publications

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“…Spontaneous contractions of smooth muscle cells were observed between days 1 and 3 in small networks containing cells with ICC-like appearance (e.g., triangular cell bodies and multiple processes) and with smooth muscle-like appearance (7,13,17). Positive immunoreactivity with the anti-c-kit antibody ACK2 confirmed that the cultures contained ICC.…”

Section: Resultsmentioning

confidence: 79%

Local presentation of Steel factor increases expression of c-kit immunoreactive interstitial cells of Cajal in culture

Rich¹,

Miller²,

Gibbons

et al. 2003

American Journal of Physiology-Gastrointestinal and Liver Physi

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The binding of Steel factor (SF) to c-kit initiates a signaling pathway essential for development and maintenance of interstitial cells of Cajal (ICC). Soluble and membrane-bound isoforms of SF are expressed in the gastrointestinal tract, but the role for either isoform in supporting ICC development is unknown. The aim of this study was to determine the role of SF in supporting ICC in culture. ICC were cultured from dissociated mouse jejunum and grown with fibroblast cell lines that produced either soluble, membrane-bound or membrane-restricted SF. ICC were identified and counted by c-kit immunoreactivity. The number of c-kit immunoreactive cells was greater in the coculture system compared with cultures grown without SF-producing fibroblasts. All forms of SF-producing fibroblasts increased ICC number in culture but physical separation of the fibroblasts from the c-kit immunoreactive cells, the addition of exogenous SF to the culture medium, or fibroblast-conditioned media did not. These results are consistent with the hypothesis that the membrane-bound form of SF preferentially contributes to expression of c-kit-positive ICC under cell culture conditions.

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Section: Resultsmentioning

confidence: 79%

Local presentation of Steel factor increases expression of c-kit immunoreactive interstitial cells of Cajal in culture

Rich¹,

Miller²,

Gibbons

et al. 2003

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…Such a calcium current, classically observed in vertebrate cardiac tissue (Hagiwara et al 1988) has been identified in other molluscs (Curtis et al 1999;Ö dblom et al 2000;Pennec et al 2004). L-type channel, in molluscs as in lower vertebrates, is thought to be the primary pathway for Ca 2?…”

Section: Discussionmentioning

confidence: 80%

Establishment of functional primary cultures of heart cells from the clam Ruditapes decussatus

Hanana¹,

Talarmin²,

Pennec³

et al. 2011

Cytotechnology

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Heart cells from the clam Ruditapes decussatus were routinely cultured with a high level of reproducibility in sea water based medium. Three cell types attached to the plastic after 2 days and could be maintained in vitro for at least 1 month: epithelial-like cells, round cells and fibroblastic cells. Fibroblastic cells were identified as functional cardiomyocytes due to their spontaneous beating, their ultrastructural characteristics and their reactivity with antibodies against sarcomeric a-actinin, sarcomeric tropomyosin, myosin and troponin T-C. Patch clamp measurements allowed the identification of ionic currents characteristic of cardiomyocytes: a delayed potassium current (I K slow ) strongly suppressed (95%) by tetraethylammonium (1 mM), a fast inactivating potassium current (I K fast ) inhibited (50%) by 4 amino-pyridine at 1 mM and, at a lower level (34%) by TEA, a calcium dependent potassium current (I KCa ) activated by strong depolarization. Three inward voltage activated currents were also characterized in some cardiomyocytes: L-type calcium current (I Ca ) inhibited by verapamil at 5 9 10 -4 M, T-type Ca 2? current, rapidly activated and inactivated, and sodium current (I Na ) observed in only a few cells after strong hyperpolarization. These two currents did not seem to be physiologically essential in the initiation of the beatings of cardiomyocytes. Potassium currents were partially inhibited by tributyltin (TBT) (1 lM) but not by okadaic acid (two marine pollutants). DNA synthesis was also demonstrated in few cultured cells using BrdU (bromo-2 0 -deoxyuridine). Observed effects of okadaic acid and TBT demonstrated that cultured heart cells from clam Ruditapes decussatus can be used as an experimental model in marine toxicology.

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“…Early studies found that LVA channels were more sensitive to block by 50 -100 M nickel than HVA channels (124,152,298). Subsequent studies found that many neuronal T-type channels required Ͼ10-fold higher concentrations for block, with many studies reporting IC 50 values of ϳ300 M ( Table 2).…”

Section: Isolated Neuronsmentioning

confidence: 99%

Molecular Physiology of Low-Voltage-Activated T-type Calcium Channels

Perez‐Reyes

2003

Physiological Reviews

1,501

1,446

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T-type Ca2+ channels were originally called low-voltage-activated (LVA) channels because they can be activated by small depolarizations of the plasma membrane. In many neurons Ca2+ influx through LVA channels triggers low-threshold spikes, which in turn triggers a burst of action potentials mediated by Na+ channels. Burst firing is thought to play an important role in the synchronized activity of the thalamus observed in absence epilepsy, but may also underlie a wider range of thalamocortical dysrhythmias. In addition to a pacemaker role, Ca2+ entry via T-type channels can directly regulate intracellular Ca2+ concentrations, which is an important second messenger for a variety of cellular processes. Molecular cloning revealed the existence of three T-type channel genes. The deduced amino acid sequence shows a similar four-repeat structure to that found in high-voltage-activated (HVA) Ca2+ channels, and Na+ channels, indicating that they are evolutionarily related. Hence, the α1-subunits of T-type channels are now designated Cav3. Although mRNAs for all three Cav3 subtypes are expressed in brain, they vary in terms of their peripheral expression, with Cav3.2 showing the widest expression. The electrophysiological activities of recombinant Cav3 channels are very similar to native T-type currents and can be differentiated from HVA channels by their activation at lower voltages, faster inactivation, slower deactivation, and smaller conductance of Ba2+. The Cav3 subtypes can be differentiated by their kinetics and sensitivity to block by Ni2+. The goal of this review is to provide a comprehensive description of T-type currents, their distribution, regulation, pharmacology, and cloning.

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Contribution of two types of calcium currents to the pacemaker potentials of rabbit sino‐atrial node cells.

Cited by 745 publications

References 34 publications

Local presentation of Steel factor increases expression of c-kit immunoreactive interstitial cells of Cajal in culture

Local presentation of Steel factor increases expression of c-kit immunoreactive interstitial cells of Cajal in culture

Establishment of functional primary cultures of heart cells from the clam Ruditapes decussatus

Molecular Physiology of Low-Voltage-Activated T-type Calcium Channels

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