A Simple Prfparation Technioue for a Microsomal Na+K+Activated at Pase from Cardiac Tisstlfs of Different Specifs

Abstract

A simple and relatively gentle technique for Isolation of a cardiac microsomal Na⁺ - K⁺- adenoslnetrIphosphatase (Na⁺ - K⁺-ATPase) Is described, consisting of one differential centrlfugatIon step followed by gel chromatography (Sepharose 4B) of the supernatant. Depending on the species (rat, guinea pig, rabbit), the preparations contained 2 to 4% of the total protein, while the mitochondrial contamination (as estimated by succinatedehydrogenase (SDH) - activity) was In the range of 2 to 10 % of the initial content. The Na⁺- K⁺ - ATPase activity was between 10 and 40 μmol P₁/mg protein/hour, corresponding to 30 to 45 % of the total activity. Further, an automatic assay for the determination of ATPase activities Is described.