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Related Experiment Video

Updated: Jun 5, 2026

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca²⁺ Transients and Membrane Currents

Published on: July 3, 2013

Porcine Left Atrial and Ventricular Thick Filaments Exhibit Distinct Resting Structures and Calcium-dependent

Lin Qi¹, Maicon Landim-Vieira¹, Hailey Flannagan¹

¹Department of Biology, Illinois Institute of Technology, Chicago, IL 60616.

Biorxiv : the Preprint Server for Biology

|June 4, 2026

Summary

Cardiac myosin filaments in the atria (LA) have a distinct structure and regulation compared to the ventricles (LV). This difference, particularly in calcium activation, highlights unique adaptations for each heart chamber and potential therapeutic targets for atrial diseases.

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Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

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Published on: November 3, 2020

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Last Updated: Jun 5, 2026

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca²⁺ Transients and Membrane Currents

Published on: July 3, 2013

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca²⁺ Transients and L-Type Calcium Current

Published on: November 3, 2020

Area of Science:

Cardiovascular Physiology
Muscle Biology
Biophysics

Background:

The heart's four chambers (atria and ventricles) have specialized roles, suggesting chamber-specific myofilament properties.
Understanding these differences is crucial for comprehending cardiac function and disease.

Purpose of the Study:

To investigate functional and structural differences in porcine left atrial (LA) and left ventricular (LV) myofilaments.
To explore chamber-specific myosin filament structure and calcium regulation in the heart.

Main Methods:

Muscle mechanics and X-ray diffraction were used to study porcine LA and LV tissue.
Myosin filament structure, force generation, stiffness, and calcium sensitivity were analyzed.

Main Results:

Atrial myosin filaments exhibit a distinct ON-like configuration in resting conditions compared to ventricular filaments.
Left ventricle generated greater force and stiffness; left atrium showed faster, calcium-independent cross-bridge cycling (kTR).
Left atrium lacks direct calcium-dependent thick filament activation, unlike the left ventricle.

Conclusions:

Left atrial myosin filaments possess a unique molecular architecture and regulatory mechanism distinct from the left ventricle.
These findings suggest evolutionary divergence in myosin regulation to meet chamber-specific functional demands.
Understanding atrial-specific mechanisms offers insights into therapeutic strategies for atrial diseases and cardiomyopathies.