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Dynamics of T-Junction Solution Switching Aimed at Patch Clamp Experiments.

Auzmendi JA, Smoler M, Moffatt L - PLoS ONE (2015)

Bottom Line: The exchange time was found to increase quadratically with the delay, although a sizeable variability remains unexplained by this relationship.This effect would be present in all tubing based devices.Present results might be of fundamental importance for the adequate design of serial compound exchangers which would be instrumental in the discovery of drugs that modulate the action of the physiological agonists of ion channels with the purpose of fine tuning their physiology.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Química Física de los Materiales, Medio Ambiente y Energía. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.

ABSTRACT
Solutions exchange systems are responsible for the timing of drug application on patch clamp experiments. There are two basic strategies for generating a solution exchange. When slow exchanges are bearable, it is easier to perform the exchange inside the tubing system upstream of the exit port. On the other hand, fast, reproducible, exchanges are usually performed downstream of the exit port. As both strategies are combinable, increasing the performance of upstream exchanges is desirable. We designed a simple method for manufacturing T-junctions (300 μm I.D.) and we measured the time profile of exchange of two saline solutions using a patch pipette with an open tip. Three factors were found to determine the timing of the solution switching: pressure, travelled distance and off-center distance. A linear relationship between the time delay and the travelled distance was found for each tested pressure, showing its dependence to the fluid velocity, which increased with pressure. The exchange time was found to increase quadratically with the delay, although a sizeable variability remains unexplained by this relationship. The delay and exchange times increased as the recording pipette moved away from the center of the stream. Those increases became dramatic as the pipette was moved close to the stream borders. Mass transport along the travelled distance between the slow fluid at the border and the fast fluid at the center seems to contribute to the time course of the solution exchange. This effect would be present in all tubing based devices. Present results might be of fundamental importance for the adequate design of serial compound exchangers which would be instrumental in the discovery of drugs that modulate the action of the physiological agonists of ion channels with the purpose of fine tuning their physiology.

No MeSH data available.


Related in: MedlinePlus

Analysis of the data at the optimal point.(A) Linear plot showing that the delay time increased linearly with the traveled distance at each propelled pressure. (B) Semi-log plot showing the relationship between the exchange time (t10-90) and the distance for each propelled pressure. (C) Log-log plot showing a power relationship that describes the exchange time as a function of the delay time for all distances and propelled pressures. Dashed line indicates the 95% prediction interval of a linear regression on the logarithms.
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pone.0133187.g004: Analysis of the data at the optimal point.(A) Linear plot showing that the delay time increased linearly with the traveled distance at each propelled pressure. (B) Semi-log plot showing the relationship between the exchange time (t10-90) and the distance for each propelled pressure. (C) Log-log plot showing a power relationship that describes the exchange time as a function of the delay time for all distances and propelled pressures. Dashed line indicates the 95% prediction interval of a linear regression on the logarithms.

Mentions: Fig 4A shows how the delay in the response increased linearly with distance. At 0.1 bar it increased from 41.44 ± 0.67 ms (n = 4) at 1 mm to 763.32 ± 0.91 ms (n = 4) at 70 mm. At 0.4 bar it increased from 17.50 ± 0.10 ms (n = 5) to 136.39 ± 1.59 ms (n = 4). A linear fit of the delay with distance allowed us to calculate the velocity of the fluid for each N2 pressure: 0.492 ± 0.003 m/s at 0.4 bar; 0.267 ± 0.001 m/s at 0.2 bar and 0.098 ± 0.002 m/s at 0.1 bar. This increase in velocity with the pressure was approximately linear (R2 = 0.98). Calculated Reynolds numbers ranged from 30 to 150 which are indicative of a laminar flow regime.


Dynamics of T-Junction Solution Switching Aimed at Patch Clamp Experiments.

Auzmendi JA, Smoler M, Moffatt L - PLoS ONE (2015)

Analysis of the data at the optimal point.(A) Linear plot showing that the delay time increased linearly with the traveled distance at each propelled pressure. (B) Semi-log plot showing the relationship between the exchange time (t10-90) and the distance for each propelled pressure. (C) Log-log plot showing a power relationship that describes the exchange time as a function of the delay time for all distances and propelled pressures. Dashed line indicates the 95% prediction interval of a linear regression on the logarithms.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4503516&req=5

pone.0133187.g004: Analysis of the data at the optimal point.(A) Linear plot showing that the delay time increased linearly with the traveled distance at each propelled pressure. (B) Semi-log plot showing the relationship between the exchange time (t10-90) and the distance for each propelled pressure. (C) Log-log plot showing a power relationship that describes the exchange time as a function of the delay time for all distances and propelled pressures. Dashed line indicates the 95% prediction interval of a linear regression on the logarithms.
Mentions: Fig 4A shows how the delay in the response increased linearly with distance. At 0.1 bar it increased from 41.44 ± 0.67 ms (n = 4) at 1 mm to 763.32 ± 0.91 ms (n = 4) at 70 mm. At 0.4 bar it increased from 17.50 ± 0.10 ms (n = 5) to 136.39 ± 1.59 ms (n = 4). A linear fit of the delay with distance allowed us to calculate the velocity of the fluid for each N2 pressure: 0.492 ± 0.003 m/s at 0.4 bar; 0.267 ± 0.001 m/s at 0.2 bar and 0.098 ± 0.002 m/s at 0.1 bar. This increase in velocity with the pressure was approximately linear (R2 = 0.98). Calculated Reynolds numbers ranged from 30 to 150 which are indicative of a laminar flow regime.

Bottom Line: The exchange time was found to increase quadratically with the delay, although a sizeable variability remains unexplained by this relationship.This effect would be present in all tubing based devices.Present results might be of fundamental importance for the adequate design of serial compound exchangers which would be instrumental in the discovery of drugs that modulate the action of the physiological agonists of ion channels with the purpose of fine tuning their physiology.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Química Física de los Materiales, Medio Ambiente y Energía. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.

ABSTRACT
Solutions exchange systems are responsible for the timing of drug application on patch clamp experiments. There are two basic strategies for generating a solution exchange. When slow exchanges are bearable, it is easier to perform the exchange inside the tubing system upstream of the exit port. On the other hand, fast, reproducible, exchanges are usually performed downstream of the exit port. As both strategies are combinable, increasing the performance of upstream exchanges is desirable. We designed a simple method for manufacturing T-junctions (300 μm I.D.) and we measured the time profile of exchange of two saline solutions using a patch pipette with an open tip. Three factors were found to determine the timing of the solution switching: pressure, travelled distance and off-center distance. A linear relationship between the time delay and the travelled distance was found for each tested pressure, showing its dependence to the fluid velocity, which increased with pressure. The exchange time was found to increase quadratically with the delay, although a sizeable variability remains unexplained by this relationship. The delay and exchange times increased as the recording pipette moved away from the center of the stream. Those increases became dramatic as the pipette was moved close to the stream borders. Mass transport along the travelled distance between the slow fluid at the border and the fast fluid at the center seems to contribute to the time course of the solution exchange. This effect would be present in all tubing based devices. Present results might be of fundamental importance for the adequate design of serial compound exchangers which would be instrumental in the discovery of drugs that modulate the action of the physiological agonists of ion channels with the purpose of fine tuning their physiology.

No MeSH data available.


Related in: MedlinePlus