High-throughput study of rabbit ventricle action potential populations in MI model

Lachaud, Q., MacQuaide, N. , Burton, F. and Smith, G. (2018) High-throughput study of rabbit ventricle action potential populations in MI model. Biophysical Journal, 114(3.S1), 625A. (doi: 10.1016/j.bpj.2017.11.3377)

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Background: Electrical activity in isolated cardiomyocytes has been widely studied using patch clamping, which offers limited throughput. Using voltage- and calcium-sensitive dyes, the electrical activity, calcium dynamics and contractility profile of cells can be measured simultaneously in approximately 100 cells per heart. This feature provides further insight into the mechanisms of excitation-contraction coupling in the failing heart. Moreover, this high-throughput methodology allows the study of large cell populations in individual hearts, offering a quantitative measure of cellular and regional heterogeneity, otherwise obscured by animal variation and undersampling. Methods: Adult rabbit cardiomyocytes were isolated from the left ventricle of infarcted (MI), control (Sham), and stock rabbits, loaded with the fluorescent, voltage-sensitive dye FluoVolt® (1:6000), and plated on to 35mm glass-bottomed plates (Krebs solution at 37°C; 1.8mM CaCl2). Left ventricle cells were serially paced at 1Hz, 2Hz and 3Hz using field stimulation (2x20mm graphite electrodes; 40V, 2ms pulse width). Separately isolated cells originating from either epicardium or endocardium were paced at 2Hz. A 10s action potential train was recorded from each cell. Results: The methodology corroborates previously published work showing an increase in mean APD90 in MI at slow rates. Mean APD90 in MI (Nanimals=6, ncells=450-800) was 374±11ms, 287±4ms, and 208±4ms at 1Hz, 2Hz and 3Hz, respectively. Mean APD90 in Sham was 336±16ms, 252±6ms, 206±1ms, at 1Hz, 2Hz, and 3Hz, respectively (Mean±S.E.M). Regional analyses (Nanimals=9, ncells=554) found AP90 was shortened in the epicardium vs. the endocardium in stock (21±6ms difference) and sham animals (37±10ms), while this difference was entirely lost in MI (P=0.323). Moreover, epicardial cell populations showed consistently higher variability than endocardial cells, across all experimental groups. This technique consequently provides accurate quantification of biological variation in individual hearts and heart regions, suggesting a strong potential for drug screening assays.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Smith, Professor Godfrey and MacQuaide, Dr Niall and Burton, Dr Francis
Authors: Lachaud, Q., MacQuaide, N., Burton, F., and Smith, G.
College/School:College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
Journal Name:Biophysical Journal
Publisher:Biophysical Society
ISSN (Online):1542-0086

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