Abstract
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.
Highlights
LIVE TISSUE SLICES ARE well-established pseudo-two-dimensional (2D) models for research into organphysiology and drug effects, in particular for brain [54] and liver [29]
Compared with single isolated cells or cell culture, slices benefit from inclusion of the various cell types that make up native tissue such as myocytes and fibroblasts in myocardium [12]
Two dye combinations were used for dual Vm and calcium transients (CaT) mapping of tissue slices: di-4-ANBDQPQ in combination with Rhod-2-AM for rabbit, and di-4-ANBDQBS with Cal-520-AM for guinea pig heart
Summary
LIVE TISSUE SLICES ARE well-established pseudo-two-dimensional (2D) models for research into organ (patho-)physiology and drug effects, in particular for brain [54] and liver [29]. As suggested by Yashura et al in the 1990s [74], cutting ventricular tissue tangentially to the epicardial surface allows for an optimized alignment of (at least near-epicardial) slices with locally prevailing cell orientation, compared with transmurally directed sections This was confirmed by Bussek et al [10], assessing the results of different cutting directions using two-photon microscopy and histology. Few studies [20, 45, 56] have used high spatial resolution optical methods to monitor electrophysiological parameters This includes our proof-of-principle-studies [45, 69] in which we employed dual Vm and CaT mapping of ventricular slices to illustrate the suitability of the approach for studying the effects of mecha-. Available programs like ImageJ [27, 61] are helpful, and more sophisticated methods have been developed for processing optical imaging data obtained from single cells and whole heart [42, 67, 75]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
