Stop the beat to see the rhythm: excitation-contraction uncoupling in cardiac research

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 321; no. 6; pp. H1005 - H1013
• Main Authors: Swift, Luther M, Kay, Matthew W, Ripplinger, Crystal M, Posnack, Nikki Gillum
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.12.2021
• Series: Getting It Right
• Subjects: Action Potentials - drug effects; Animals; Best practice; Biomedical Research; Calcium (intracellular); Cells, Cultured; Contraction; Electrophysiology; Excitation; Excitation Contraction Coupling - drug effects; Excitation-contraction coupling; Fluorescent indicators; Heart; Heart function; Heart Rate - drug effects; Heterocyclic Compounds, 4 or More Rings - pharmacology; Humans; Imaging techniques; Literature reviews; Mapping; Metabolism; Myocardial Contraction - drug effects; Myocytes, Cardiac - drug effects; Myocytes, Cardiac - metabolism; Optical communication; Parameter sensitivity; Signal distortion; Time Factors; Tissues; Voltage-Sensitive Dye Imaging; excitation-contraction uncoupler; optical mapping; blebbistatin; cardiac physiology
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00477.2021

Optical mapping is an imaging technique that is extensively used in cardiovascular research, wherein parameter-sensitive fluorescent indicators are used to study the electrophysiology and excitation-contraction coupling of cardiac tissues. Despite many benefits of optical mapping, eliminating motion artifacts within the optical signals is a major challenge, as myocardial contraction interferes with the faithful acquisition of action potentials and intracellular calcium transients. As such, excitation-contraction uncoupling agents are frequently used to reduce signal distortion by suppressing contraction. When compared with other uncoupling agents, blebbistatin is the most frequently used, as it offers increased potency with minimal direct effects on cardiac electrophysiology. Nevertheless, blebbistatin may exert secondary effects on electrical activity, metabolism, and coronary flow, and the incorrect administration of blebbistatin to cardiac tissue can prove detrimental, resulting in erroneous interpretation of optical mapping results. In this "Getting It Right" perspective, we briefly review the literature regarding the use of blebbistatin in cardiac optical mapping experiments, highlight potential secondary effects of blebbistatin on cardiac electrical activity and metabolic demand, and conclude with the consensus of the authors on best practices for effectively using blebbistatin in optical mapping studies of cardiac tissue.