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Characterization of the Prokaryotic Sodium Channel NavSp Pore with a Microfluidic Bilayer Platform.

Saha SC, Henderson AJ, Powl AM, Wallace BA, de Planque MR, Morgan H - PLoS ONE (2015)

Bottom Line: The platform allows up to 6 bilayers to be analysed simultaneously.Proteoliposomes were incorporated into suspended lipid bilayers formed within the microfluidic bilayer chips.The chips provide access to bilayers from either side, enabling the fast and controlled titration of compounds.

View Article: PubMed Central - PubMed

Affiliation: Electronics and Computer Science, University of Southampton, Southampton, SO17 1BJ, United Kingdom.

ABSTRACT
This paper describes the use of a newly-developed micro-chip bilayer platform to examine the electrophysiological properties of the prokaryotic voltage-gated sodium channel pore (Na(v)Sp) from Silicibacter pomeroyi. The platform allows up to 6 bilayers to be analysed simultaneously. Proteoliposomes were incorporated into suspended lipid bilayers formed within the microfluidic bilayer chips. The chips provide access to bilayers from either side, enabling the fast and controlled titration of compounds. Dose-dependent modulation of the opening probability by the channel blocking drug nifedipine was measured and its IC50 determined.

No MeSH data available.


Related in: MedlinePlus

Modulation of ion channel properties by drugs.(a) Single channel current recordings of the NavSp pore for different concentration of nifedipine. (b) Channel open probability at different concentrations of the drug. Error bars are the standard deviations of measurements from ≥ 2 individual bilayers.
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pone.0131286.g003: Modulation of ion channel properties by drugs.(a) Single channel current recordings of the NavSp pore for different concentration of nifedipine. (b) Channel open probability at different concentrations of the drug. Error bars are the standard deviations of measurements from ≥ 2 individual bilayers.

Mentions: The calcium- and sodium-channel blocker nifedipine is used to treat high blood pressure and to control angina [17,18]. Nifedipine has been shown to reduce channel opening times and block prokaryotic sodium channels such as NaChBac [6] as well as eukaryotic calcium channels. Nifedipine was used in this study in preference to other channel blockers such as mibefradil due to its higher solubility in aqueous solutions. Upon addition of nifedipine to only one side of the membrane, complete blocking was unachievable even at very high concentrations, implying that the channels probably insert in both orientations so that the drug is unable to reach the binding sites of a large proportion of channels. Therefore, the half inhibitory concentration IC50 was measured by adding different concentrations of drug to both sides of the bilayer. Drugs were added after characteristic channel activity was established, since the gating behaviour (the mean open time) can vary from experiment to experiment. The open time probability was normalized against opening times for the channel in the absence of nifedipine. The data is plotted in Fig 3 and the IC50 was calculated to be 2.95 μM.


Characterization of the Prokaryotic Sodium Channel NavSp Pore with a Microfluidic Bilayer Platform.

Saha SC, Henderson AJ, Powl AM, Wallace BA, de Planque MR, Morgan H - PLoS ONE (2015)

Modulation of ion channel properties by drugs.(a) Single channel current recordings of the NavSp pore for different concentration of nifedipine. (b) Channel open probability at different concentrations of the drug. Error bars are the standard deviations of measurements from ≥ 2 individual bilayers.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493117&req=5

pone.0131286.g003: Modulation of ion channel properties by drugs.(a) Single channel current recordings of the NavSp pore for different concentration of nifedipine. (b) Channel open probability at different concentrations of the drug. Error bars are the standard deviations of measurements from ≥ 2 individual bilayers.
Mentions: The calcium- and sodium-channel blocker nifedipine is used to treat high blood pressure and to control angina [17,18]. Nifedipine has been shown to reduce channel opening times and block prokaryotic sodium channels such as NaChBac [6] as well as eukaryotic calcium channels. Nifedipine was used in this study in preference to other channel blockers such as mibefradil due to its higher solubility in aqueous solutions. Upon addition of nifedipine to only one side of the membrane, complete blocking was unachievable even at very high concentrations, implying that the channels probably insert in both orientations so that the drug is unable to reach the binding sites of a large proportion of channels. Therefore, the half inhibitory concentration IC50 was measured by adding different concentrations of drug to both sides of the bilayer. Drugs were added after characteristic channel activity was established, since the gating behaviour (the mean open time) can vary from experiment to experiment. The open time probability was normalized against opening times for the channel in the absence of nifedipine. The data is plotted in Fig 3 and the IC50 was calculated to be 2.95 μM.

Bottom Line: The platform allows up to 6 bilayers to be analysed simultaneously.Proteoliposomes were incorporated into suspended lipid bilayers formed within the microfluidic bilayer chips.The chips provide access to bilayers from either side, enabling the fast and controlled titration of compounds.

View Article: PubMed Central - PubMed

Affiliation: Electronics and Computer Science, University of Southampton, Southampton, SO17 1BJ, United Kingdom.

ABSTRACT
This paper describes the use of a newly-developed micro-chip bilayer platform to examine the electrophysiological properties of the prokaryotic voltage-gated sodium channel pore (Na(v)Sp) from Silicibacter pomeroyi. The platform allows up to 6 bilayers to be analysed simultaneously. Proteoliposomes were incorporated into suspended lipid bilayers formed within the microfluidic bilayer chips. The chips provide access to bilayers from either side, enabling the fast and controlled titration of compounds. Dose-dependent modulation of the opening probability by the channel blocking drug nifedipine was measured and its IC50 determined.

No MeSH data available.


Related in: MedlinePlus