Na /K ATPase-Ca 1.2 nanodomain differentially regulates intracellular [Na ], [Ca ] and local adrenergic signaling in cardiac myocytes.

Background: The intracellular Na concentration ([Na ] ) is a crucial but understudied regulator of cardiac myocyte function. The Na /K ATPase (NKA) controls the steady-state [Na ] and thereby determines the set-point for intracellular Ca . Here, we investigate the nanoscopic organization and local adrenergic regulation of the NKA macromolecular complex and how it differentially regulates the intracellular Na and Ca homeostases in atrial and ventricular myocytes.

Camera-based Measurements of Intracellular [Na+] in Murine Atrial Myocytes.

Intracellular sodium concentration ([Na]i) is an important regulator of intracellular Ca. Its study provides insight into the activation of the sarcolemmal Na/Ca exchanger, the behavior of voltage-gated Na channels and the Na,K-ATPase. Intracellular Ca signaling is altered in atrial diseases such as atrial fibrillation.

Region [corrected] of slowed conduction acts as core for spiral wave reentry in cardiac cell monolayers.

Pathophysiological heterogeneity in cardiac tissue is related to the occurrence of arrhythmias. Of importance are regions of slowed conduction, which have been implicated in the formation of conduction block and reentry. Experimentally, it has been a challenge to produce local heterogeneity in a manner that is both reversible and well controlled.