Cardiac cushions modulate action potential phenotype during heart development [corrected]

Area of Science:

• Cardiovascular Biology
• Developmental Biology
• Biophysics

Background:

• The extracellular matrix (ECM) is crucial for cardiac function, but its role in early heart development, particularly in electrical activity, is understudied.
• Cardiac cushions are transient embryonic structures rich in ECM, essential for heart valve and septa formation.

Purpose of the Study:

• To investigate the impact of cardiac cushion extracellular matrix on cardiomyocyte electrical activity during heart development.
• To determine if fibronectin, a major ECM component, can replicate the effects of cardiac cushion tissue on action potential phenotype.

Main Methods:

• Studied the direct effect of cardiac cushion ECM on cardiomyocytes from different heart regions.
• Assessed changes in action potential phenotype upon ECM contact.
• Investigated the specific effects of fibronectin on ion currents and intracellular calcium.

Main Results:

• Cardiac cushion ECM alters the action potential phenotype of cardiomyocytes through direct contact.
• Fibronectin partially mimics the effects of cushion tissue on action potential changes.
• Fibronectin enhances L-type calcium current (I(Ca) (2+)) and acutely increases cytosolic calcium levels.

Conclusions:

• The composition of the cardiac ECM during development is a significant factor in establishing electrical activity patterns in the developing heart.
• Fibronectin plays a role in modulating cardiomyocyte electrical properties within the developing cardiac environment.