Validation of Na+, K+-ATPase Isoform Endogenous to Cardiomyocytes for High Throughput Rb Uptake Assay using Cor.At® Cardiomyocytes & ICR8000™

Introduction

Human Na+, K+ ATPase is the target for cardioglycosides such as digitoxin and digoxin which are used in the treatment of congestive heart failure and related conditions; thus, it is emerging as an important drug target. The Na+, K+ pump generates
electrochemical gradients that are used to drive the coupled transport of many ions and nutrients across the plasma membrane as it actively exports three Na+ ions with the concomitant import of two K+ ions hydrolyzing one ATP molecule in the process.

In non-cell-based assays, the activity of Na+, K+ ATPase has been determined by using purified enzyme preparations to hydrolyze ATP. In cell-based assays, the techniques such as patch clamping, fluorescence, H3-Ouabain binding, and radio-tracer (Rubidium
86), and cold Rubidium flux assays have been used in either recombinant cell lines or in cells other than primary cardiomyocytes. However, the primary cardiomyocytes cannot be used, as they lack homogeneity, sensitivity and surface binding properties,
in developing cell based assays in a HTS format.

In view of the availability of standardized pure cardiac myocytes with functional expression of all essential cardiac ion channels, Aurora Biomed validated Na+, K+ ATPase in cultured Cor.At® cardiomyocytes derived from transgenic mouse embryonic stem cells.