Talking about bioelectrical potentials using rings of the mesenteric artery without glass micropipettes

In the present study, a practical activity is proposed to adopt an experimental approach to demonstrate the relationship between the equilibrium potential for K(+) and transmembrane electrical potential without glass micropipettes. A conventional setup for recording contractile activity of isolated...

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Bibliographic Details
Published in:Advances in physiology education 2012-12, Vol.36 (4), p.336-344
Main Authors: Ribeiro-Filho, H V, Brito, T S, Lima, F J B, Pinho, J P M, Sousa, D F, Silva, M T B, de Siqueira, R J B, Cosker, F, Bastos, V P D, Santos, A A, Magalhães, P J C
Format: Article
Language:English
Subjects:
Animals
Glass
Humans
Isometric Contraction - physiology
Male
Membrane Potentials - physiology
Membranes
Mesenteric Arteries - physiology
Organ Culture Techniques - instrumentation
Organ Culture Techniques - methods
Permeability
Physiology
Physiology - education
Physiology - instrumentation
Physiology - methods
Potassium
Rats
Rats, Wistar
Rodents
Science education
Students
Veins & arteries
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Summary:In the present study, a practical activity is proposed to adopt an experimental approach to demonstrate the relationship between the equilibrium potential for K(+) and transmembrane electrical potential without glass micropipettes. A conventional setup for recording contractile activity of isolated smooth muscle preparations was used based on the events elegantly described by Somlyo and Somlyo in the 1960s. They showed that, in response to a given stimulus, smooth muscle cells may contract, recruiting electromechanical or pharmacomechanical coupling by mechanisms that involve, or not, changes in transmembrane potential, respectively. By means of contractions and relaxations of a ring-like preparation from the rat mesenteric artery, it is possible to observe the functional consequences of handling K(+) concentration in the extracellular compartment and the effects caused by opening K(+) channels in that preparation, which are significant when the cell membrane establishes an electrical potential difference between intra- and extracellular compartments (driven mainly by K(+) permeability under resting conditions). The effects observed by students fit well with values predicted by Nernst and Goldman-Hodgin-Katz equations, and we demonstrated that the activity is able to improve students' comprehension regarding basic principles of bioelectricity.
ISSN:1043-4046
1522-1229
DOI:10.1152/advan.00050.2012