Contribution of Aquaporins to Cellular Water Transport Observed by a Microfluidic Cell Volume Sensor

Heo, Jeong Wook; Meng, Fanjie; Hua, Susan Z.

doi:10.1021/ac8008498

Cited by 33 publications

(25 citation statements)

References 33 publications

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“…This result is in good agreement with previously published studies, reporting that MDCK cells show a volume decrease that is linearly dependent on the osmolarity of the stimulation buffer (Roy and Sauve, 1987). (ii) Following the data analysis procedures of other groups (Heo et al, 2008;Maric et al, 2001) we fitted the increase of the SPR signal after stimulating with a 340 mOsm/kg buffer using a mono-exponential function (Fig. 2c).…”

Section: Spr Measurement Of Cell Volume Changessupporting

confidence: 91%

Label-free and time-resolved measurements of cell volume changes by surface plasmon resonance (SPR) spectroscopy

Robelek

Wegener

2010

Biosensors and Bioelectronics

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Section: Spr Measurement Of Cell Volume Changessupporting

confidence: 91%

Label-free and time-resolved measurements of cell volume changes by surface plasmon resonance (SPR) spectroscopy

Robelek

Wegener

2010

Biosensors and Bioelectronics

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“…The solution flow rate was controlled using a syringe pump (PHD 22/2200, Harvard Apparatus, Holliston, MA). The data was plotted as the ratio of cell volume change to the resting cell volume as previously described [20, 21, 23]. To measure the resistance of the empty chamber, after an experiment was finished the chamber was perfused with a detergent (1% Triton X-100) to permeabilize the cells and the chamber was then rinsed with isotonic solution.…”

Section: Methodsmentioning

confidence: 99%

Shear-induced Volume Decrease in MDCK Cells

Heo

Sachs

Wang

et al. 2012

Cell Physiol Biochem

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Using a microfluidic cell volume sensor we measured the change in the cell volume of Madin-Darby Canine Kidney (MDCK) cells induced by shear stress. An increase in shear stress from 0.2 to 2.0 dyn/cm² resulted in a volume decrease to a steady state volume ∼ 20 – 30 % smaller than the initial resting cell volume. Independent experiments based on fluorescence quenching confirmed the volume reduction. This shear-induced cell shrinkage was irreversible on the time scale of the experiment (∼ 30 min). Treatment of 0.1 µM Hg²⁺ significantly inhibited the volume decrease, suggesting that the shear-induced cell shrinkage is associated with water efflux through aquaporins. The volume decrease cannot be inhibited by 75 mM TEA, 100 µM DIDS, or 100 µM Gd³⁺ suggesting that volume reduction is not directly mediated by K⁺ and Cl^-channels that typically function during regulatory volume decrease (RVD), nor is it through cationic stretch-activated ion channels (SACs). The process also appears to be Ca²⁺ independent because it was insensitive to intracellular Ca²⁺ level. Since cell volume is determined by the intracellular water content, we postulate that the shear induced reductions in cell volume may arise from increased intracellular hydrostatic pressure as the cell is deformed under flow, which promotes the efflux of water. The increase in internal pressure in a deformable object under the flow is supported by the finite element mechanical model.

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“…There are a vast number of papers on cell volume regulation [55,98,142–147] invoking various ion channels such as the BK channels [148] and other K + channels [149] , chloride channels [147,150–152] as well as neutral transporters [143,153,154] and water transporters [155–157] as well as the cytoskeleton [26–29,98,139,158] and host of calcium and other intracellular messengers [15,159–161] . Given the vast scale of modulators and potential effectors, it is unwise to think of cell volume as a specific stimulus.…”

Section: Stimulating Cellsmentioning

confidence: 99%

Mechanical transduction by ion channels: A cautionary tale

Sachs¹

2015

WJN

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Mechanical transduction by ion channels occurs in all cells. The physiological functions of these channels have just begun to be elaborated, but if we focus on the upper animal kingdom, these channels serve the common sensory services such as hearing and touch, provide the central nervous system with information on the force and position of muscles and joints, and they provide the autonomic system with information about the filling of hollow organs such as blood vessels. However, all cells of the body have mechanosensitive channels (MSCs), including red cells. Most of these channels are cation selective and are activated by bilayer tension. There are also K+ selective MSCs found commonly in neurons where they may be responsible for both general anesthesia and knockout punches in the boxing ring by hyperpolarizing neurons to reduce excitability. The cationic MSCs are typically inactive under normal mechanical stress, but open under pathologic stress. The channels are normally inactive because they are shielded from stress by the cytoskeleton. The cationic MSCs are specifically blocked by the externally applied peptide GsMtx4 (aka, AT-300). This is the first drug of its class and provides a new approach to many pathologies since it is nontoxic, non-immunogenic, stable in a biological environment and has a long pharmacokinetic lifetime. Pathologies involving excessive stress are common. They produce cardiac arrhythmias, contraction in stretched dystrophic muscle, xerocytotic and sickled red cells, etc. The channels seem to function primarily as “fire alarms”, providing feedback to the cytoskeleton that a region of the bilayer is under excessive tension and needs reinforcing. The eukaryotic forms of MSCs have only been cloned in recent years and few people have experience working with them. “Newbies” need to become aware of the technology, potential artifacts, and the fundamentals of mechanics. The most difficult problem in studying MSCs is that the actual stimulus, the force applied to the channel, is not known. We don’t have direct access to the channels themselves but only to larger regions of the membrane as seen in patches. Cortical forces are shared by the bilayer, the cytoskeleton and the extracellular matrix. How much of an applied stimulus reaches the channel is unknown. Furthermore, many of these channels exist in spatial domains where the forces within a domain are different from forces outside the domain, although we often hope they are proportional. This review is intended to be a guide for new investigators who want to study mechanosensitive ion channels.

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Contribution of Aquaporins to Cellular Water Transport Observed by a Microfluidic Cell Volume Sensor

Cited by 33 publications

References 33 publications

Label-free and time-resolved measurements of cell volume changes by surface plasmon resonance (SPR) spectroscopy

Label-free and time-resolved measurements of cell volume changes by surface plasmon resonance (SPR) spectroscopy

Shear-induced Volume Decrease in MDCK Cells

Mechanical transduction by ion channels: A cautionary tale

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