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

• Autor(a) principal: Ribeiro-Filho, Helder Veras
• Data de Publicação: 2012
• Outros Autores: Brito, Teresinha Silva de, Lima, F. J. B., Pinho, J. P. M., Sousa, D. F., Silva, Moisés Tolentino Bento da, Siqueira, Rodrigo Jose Bezerra de, Cosker, F., Bastos, V. P. D., Santos, Armenio Aguiar dos, Magalhães, Pedro Jorge Caldas
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/5697
• topic: Potássio

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.