Electrical gradients across an ion-exchange membrane in student's artificial cell.

Manalis, Richard S.; Hastings, L.

doi:10.1152/jappl.1974.36.6.769

Cited by 7 publications

(5 citation statements)

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“…This model has several advantages compared with those previously published (1,4,14,18). First, it does not require the use of an Ussing chamber.…”

Section: Inquiry Applicationmentioning

confidence: 92%

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Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements

Shlyonsky

2013

Advances in Physiology Education

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In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and n-decane. The electrical resistance and potential difference across these membranes can be easily measured using a low-cost volt-ohm meter and home-made Ag/AgCl electrodes. The advantage of the model is the lack of ionic selectivity of the membrane, which can be modified by the introduction of different ionophores to the organic liquid mixture. A membrane treated with the mixture containing valinomycin generates voltages from -53 to -25 mV in the presence of a 10-fold KCl gradient (in to out) and from -79 to -53 mV in the presence of a bi-ionic KCl/NaCl gradient (in to out). This latter bi-ionic gradient potential reverses to a value from +9 to +20 mV when monensin is present in the organic liquid mixture. Thus, the model can be build stepwise, i.e., all factors leading to the development of diffusion potentials can be introduced sequentially, helping students to understand the quantitative relationships of ionic gradients and differential membrane permeability in the generation of cell electrical signals.

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“…This model has several advantages compared with those previously published (1,4,14,18). First, it does not require the use of an Ussing chamber.…”

Section: Inquiry Applicationmentioning

confidence: 92%

“…However, this kind of experiment involves some non-negligible ethical considerations. Efficient replacement of live tissue has been suggested in the form of artificial membranes made of either polysulphonic ion exchange resin (1) or ion-selective filter membranes (4,14) or even dialysis membranes (18). All of these membranes have intrinsic ion selectivity.…”

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confidence: 99%

Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements

Shlyonsky

2013

Advances in Physiology Education

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“…However, students still encounter problems in understanding neuroscience topics. Even university students have problems understanding abstract concepts such as the emergence of the resting potential (Manalis and Hastings, 1974;Barry, 1990). However, more recent studies also reveal existing misconceptions, for example, regarding membrane potential (Silverthorn, 2002) or synaptic transmission (Montagna et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Motivation and Technology Acceptance in a Neuroscience Student Lab—An Empirical Comparison Between Virtual Experiments With and Without Hands-on Elements

2022

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Out-of-school laboratories, also called student labs, are an advantageous opportunity to teach biological subjects. Particularly in the case of complex fields such as neurobiology, student labs offer the opportunity to learn about difficult topics in a practical way. Due to numerous advantages, digital student labs are becoming increasingly popular nowadays. In this study, we investigated the effect of an electrophysiological setup for a virtual experiment with and without hands-on elements on participant motivation and technology acceptance. For this purpose, 235 students were questioned during a student laboratory day. The surveyed students showed high motivation and technology acceptance for the virtual experiment. In the comparison, the electrophysiological setup with hands-on elements performs better in the intrinsic components than the setup without hands-on elements: Thus, the hands-on approach is rated as more interesting and the perceived enjoyment scores higher. Nevertheless, both experimental groups show high values, so that the results of the study support the positive influence of digital laboratory as well as a positive influence of hands-on elements.

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“…However, teaching the concept of a membrane potential is very difficult (11). Students often become confused with the bewildering array of membrane pumps and channels and transmembrane ion gradi-…”

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confidence: 99%

A simple, inexpensive method for teaching how membrane potentials are generated.

Moran

Denton

Wilson

et al. 1999

Advances in Physiology Education

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We have developed a simple laboratory exercise that uses an inexpensive dialysis membrane (molecular weight cutoff = 100) to illustrate the generation of membrane potentials (Vm) across plasma membranes of animal cells. A piece of membrane approximately 2.0 cm2 is mounted in an Ussing-like chamber. One chamber half is designated cytosol and the other half external. Chamber sidedness helps students relate their findings to those of real cells. As in real cells, outward directed K+ concentration gradients [high cytosolic K+ concentration ([K+]c) and low extracellular K+ concentration] generate cytosol electrically negative Vm with a slope of approximately -45 mV/decade change in [K+]c. The polarity of Vm reflects the outward flow of potassium ions because flow of the larger counterion, H2PO4-, is restricted to the pores in the membrane. A slope less than Nernstian (<59 mV/decade) suggests that the membrane is slightly permeable to H2PO4-. Importantly, this facilitates teaching the use of the Nernst equation to quantify the relationship between ion concentration ratios across membranes and magnitude of Vm. For example, students use their data and calculate a permeability ratio PK/PH2PO4 that corresponds to a slope of approximately 24% less than Nernstian. This calculation shows that Nernstian slopes are achieved only when permeability to the counterion is zero. Finally, students use the concept of membrane capacitance to calculate the number of ions that cross the membrane. They learn where these ions are located and why the bulk solutions conform to the principle of electroneutrality.

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Electrical gradients across an ion-exchange membrane in student's artificial cell.

Cited by 7 publications

References 0 publications

Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements

Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements

Motivation and Technology Acceptance in a Neuroscience Student Lab—An Empirical Comparison Between Virtual Experiments With and Without Hands-on Elements

A simple, inexpensive method for teaching how membrane potentials are generated.

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