Cardiac tissue slices: preparation, handling, and successful optical mapping

Area of Science:

• Cardiovascular Research
• Physiology
• Biomedical Engineering

Background:

• Cardiac tissue slices are emerging as valuable models for electrophysiology and pharmacology.
• Optimized preparation and handling are essential for reliable experimental outcomes.

Purpose of the Study:

• To provide a detailed protocol for preparing and optically mapping cardiac ventricular tissue slices.
• To investigate the recovery dynamics of action potential duration (APD) and calcium transients (CaT) post-slicing.
• To establish methods for reproducible electrophysiological and calcium mapping studies.

Main Methods:

• Ventricular tissue slices from guinea pigs and rabbits were prepared using a microtome (350-400 µm thickness).
• Optical mapping of transmembrane potential and intracellular CaT was performed.
• Postcutting recovery periods were determined using exponential fitting.
• Electromechanical uncouplers (2,3-butanedione 2-monoxime or blebistatin) and buffer solutions were evaluated.
• Multipoint and field stimulation techniques were employed for characterizing intrinsic patterns.

Main Results:

• Tissue slices preserved essential action potential properties.
• Significant recovery periods were identified: 36 min for guinea pigs and 63 min for rabbits.
• APD increase post-cutting was attributed to cold solution exposure, not tissue injury.
• No significant difference in recovery dynamics was observed with different uncouplers.
• Combined stimulation methods are recommended to avoid source-sink effects.

Conclusions:

• A detailed protocol for reproducible cardiac tissue slice preparation and optical mapping is presented.
• Understanding post-slicing recovery is critical for accurate electrophysiological measurements.
• This methodology supports reliable investigations into cardiac AP and CaT dynamics.