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Cardiac tissue slices are becoming increasingly popular as a model system for cardiac electrophysiology and pharmacology research and development. Here, we describe in detail the preparation, handling, and optical mapping of transmembrane potential and intracellular free calcium concentration transients (CaT) in ventricular tissue slices from guinea pigs and rabbits. Slices cut in the epicardium-tangential plane contained well-aligned in-slice myocardial cell strands ("fibers") in subepicardial and midmyocardial sections. Cut with a high-precision slow-advancing microtome at a thickness of 350 to 400 μm, tissue slices preserved essential action potential (AP) properties of the precutting Langendorff-perfused heart. We identified the need for a postcutting recovery period of 36 min (guinea pig) and 63 min (rabbit) to reach 97.5% of final steady-state values for AP duration (APD) (identified by exponential fitting). There was no significant difference between the postcutting recovery dynamics in slices obtained using 2,3-butanedione 2-monoxime or blebistatin as electromechanical uncouplers during the cutting process. A rapid increase in APD, seen after cutting, was caused by exposure to ice-cold solution during the slicing procedure, not by tissue injury, differences in uncouplers, or pH-buffers (bicarbonate; HEPES). To characterize intrinsic patterns of CaT, AP, and conduction, a combination of multipoint and field stimulation should be used to avoid misinterpretation based on source-sink effects. In summary, we describe in detail the preparation, mapping, and data analysis approaches for reproducible cardiac tissue slice-based investigations into AP and CaT dynamics.

Original publication

DOI

10.1152/ajpheart.00556.2014

Type

Journal article

Journal

Am J Physiol Heart Circ Physiol

Publication Date

01/05/2015

Volume

308

Pages

H1112 - H1125

Keywords

heart, high spatial resolution, live tissue slices, multiparametric, optical mapping, voltage- and calcium-sensitive dyes, Action Potentials, Animals, Calcium Signaling, Cardiac Pacing, Artificial, Cold Temperature, Female, Guinea Pigs, In Vitro Techniques, Kinetics, Male, Microtomy, Myocardium, Perfusion, Rabbits, Recovery of Function, Signal Processing, Computer-Assisted, Tissue Survival, Voltage-Sensitive Dye Imaging