An intuitive approach to understanding the resting membrane potential

Cardozo, David Lopes

doi:10.1152/advan.00049.2016

Cited by 23 publications

(19 citation statements)

References 17 publications

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“…Thus, in injured cardiomyocytes, K + ions were restrained from being transported into the cells, causing a decrease in their cytosolic concentration but an increase in their extracellular concentration. Based on the Nernst equation [3], this generates a significant difference in the resting membrane potential between the normal and injured cardiac muscles. As we recently demonstrated in frog hearts exposed to high K + solution [11], such an electrical difference in cardiomyocytes would create the "currents of injury", causing the ST segment changes shown in Fig.…”

Section: Fig 1 Induction Of Subepicardial Burn Injury In Bullfrog Hmentioning

confidence: 99%

Reciprocal ST segment changes reproduced in burn-induced subepicardial injury model in bullfrog heart

Kazama

Takamura

Yamada

et al. 2020

The Journal of Veterinary Medical Science

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In our previous studies, by simply inducing burn injuries on bullfrog hearts or partially exposing their surface to high-potassium (K +) solution, we could reproduce a ST segment elevation in the electrocardiogram (ECG), which is a characteristic finding in human ischemic heart disease. In the present study, using our burn-induced subepicardial injury model, we could additionally reproduce "reciprocal" ST segment changes for the first time in frog hearts, mimicking those observed in human acute myocardial infarction. Immunohistochemistry demonstrated markedly decreased Na + /K +-ATPase protein expression in the ventricular surface after the burn injury. The loss of this pump expression in injured cardiomyocytes was thought to be responsible for the creation of "currents of injury" and the subsequent ST segment changes observed in acute myocardial infarction. KEY WORDS: acute myocardial infarction, bullfrog heart, Na + /K +-ATPase expression, reciprocal ST segment change Acute coronary syndrome (ACS, formerly called "ischemic heart disease"), including acute myocardial infarction and unstable angina pectoris, is one of the leading causes of death worldwide [1, 12, 14]. To rapidly diagnose acute myocardial infarction and improve the outcome, the electrocardiogram (ECG) is the most useful test in patients with possible myocardial ischemia [16]. However, not all patients with acute myocardial infarction present typical ECG findings represented by an elevation of the ST segment, which is the interval between the ventricular depolarization and repolarization [13]. Additionally, an elevation of this segment is also observed in other normal or abnormal cardiac conditions, such as early repolarization, right bundle-branch block, left ventricular hypertrophy or pericarditis [9]. "Reciprocal" ST segment change, which is frequently observed in acute anterior or inferior myocardial infarction, is defined as an ST segment depression in leads opposite to those that reflect an ST segment elevation [17]. Since reciprocal ST segment change is specifically noted in acute myocardial infarction, the presence of this change strongly supports its diagnosis [2, 18] and also reflects the extent of myocardial ischemia [6]. In our previous studies, by simply inducing burn injuries on the bullfrog heart or partially exposing the heart surface to high-potassium (K +) solution, we were able to reproduce an ST segment elevation in the ECG, which is a characteristic finding in human ischemic heart disease [7, 11]. Here, using our burn-induced subepicardial injury model, we could reproduce reciprocal ST segment changes in frog hearts for the first time that mimicked those observed in human acute myocardial infarction. By immunohistochemistry, we additionally examined the Na + /K +-ATPase protein expression in burned heart ventricle and revealed the physiological mechanisms underlying the ST segment changes in ECG. Adult male bullfrogs, weighing 450 to 550 g (n=12), were purchased from Ohuchi Shōten (Saitama, Japan). After initial inhalation with...

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Section: Fig 1 Induction Of Subepicardial Burn Injury In Bullfrog Hmentioning

confidence: 99%

Reciprocal ST segment changes reproduced in burn-induced subepicardial injury model in bullfrog heart

Kazama

Takamura

Yamada

et al. 2020

The Journal of Veterinary Medical Science

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“…These topics require the teacher to link necessary concepts from different previously studied subjects, hindering the success of the teaching-learning process (7). Different strategies have been developed to teach these themes (10,11,29,39,45). Many studies have described models using animals or physiology laboratory materials to explain membrane and action potential.…”

mentioning

confidence: 99%

“…Cardozo (11) created a model using springs to explain the rela-tionship between ionic conductance and potential across the membrane. In 2016, the same author and colleagues (10) described an intuitive way to understand how membrane potential is established by the concentration gradient of K ϩ ions, using simple principles familiar to high school graduates, as, for example, ions move randomly and charged ions are attracted by the opposite and are repelled by the same electric charge. Rodrigues-Falces (39) developed a model to explain the electrical behavior of the action potential in terms of elementary electrical sources, using graphical representations.…”

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confidence: 99%

Effect of an educational game on university students’ learning about action potentials

Luchi

Montrezor

Marcondes

2017

Advances in Physiology Education

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The aim of this study was to evaluate the effect of an educational game that is used for teaching the mechanisms of the action potentials in cell membranes. The game was composed of pieces representing the intracellular and extracellular environments, ions, ion channels, and the Na-K-ATPase pump. During the game activity, the students arranged the pieces to demonstrate how the ions move through the membrane in a resting state and during an action potential, linking the ion movement with a graph of the action potential. To test the effect of the game activity on student understanding, first-year dental students were given the game to play at different times in a series of classes teaching resting membrane potential and action potentials. In all experiments, students who played the game performed better in assessments. According to 98% of the students, the game supported the learning process. The data confirm the students' perception, indicating that the educational game improved their understanding about action potentials.

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Section: Conversion Of Classical I–v Relationships To Modern Conventionmentioning

confidence: 99%

“…This introduces a fundamental concept that must be understood by students, namely the application of the Nernst equation to describe the potential that results from uneven distribution of ions across semi-permeable cell membranes. This has been recently covered in a series of four papers (Cardozo, 2016;Crowther, 2017;Sawyer et al 2017;Brown, 2018), which, if read sequentially, provide the student with the requisite information on the topic. After mastering the Hodgkin and Katz paper, students can proceed to the five Hodgkin and Huxley papers, which I have also updated to the modern convention, and which are available as supporting information to the original papers, and as part of a Virtual Issue on The Journal of Physiology's website: jp.physoc.org.…”

mentioning

confidence: 99%

The classics updated, or an act of electrophysiological sacrilege?

Brown

2019

The Journal of Physiology

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An intuitive approach to understanding the resting membrane potential

Cited by 23 publications

References 17 publications

Reciprocal ST segment changes reproduced in burn-induced subepicardial injury model in bullfrog heart

Reciprocal ST segment changes reproduced in burn-induced subepicardial injury model in bullfrog heart

Effect of an educational game on university students’ learning about action potentials

The classics updated, or an act of electrophysiological sacrilege?

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