A Protocol for Transverse Cardiac Slicing and Optical Mapping in Murine Heart

Area of Science:

• Cardiovascular Research
• Physiology
• Biomedical Engineering

Background:

• Thin living tissue slices offer a novel in vitro model for cardiac electrophysiological research.
• These models, derived from various mammalian hearts, are valuable for preclinical and translational studies.
• Existing methods lack the precision for detailed regional analysis of cardiac electrical activity.

Purpose of the Study:

• To describe a detailed methodology for preparing mouse heart transverse slices for optical imaging.
• To establish a high-throughput platform for studying cardiac electrophysiology in an organotypic pseudo-2D model.
• To enable precise measurement of transmembrane potential (Vm) and calcium transients (CaT) with high spatial and temporal resolution.

Main Methods:

• Detailed protocol for mouse heart transverse slicing.
• High-throughput optical imaging techniques for Vm and CaT.
• Preparation of successive ventricular slices to reconstruct original heart geometry.

Main Results:

• Robust interrogation of Vm and CaT throughout the entire heart with exceptional regional precision.
• Ability to compare successive slices for detailed analysis of cardiac geometry.
• Profiling of transmural and regional gradients in Vm and CaT, including alternans under stress or pathological conditions.

Conclusions:

• The described protocol provides a powerful platform for studying electrical and calcium handling heterogeneity in the heart.
• This method allows for precise characterization of regional and transmural differences in cardiac electrophysiology.
• Integration with optogenetics enables cell-type-specific studies of Vm and CaT.