Na-K ATP ase inhibition induces high energy phosphates depletion and intracellular acidosis. A 31P NMR study of the isolated perfused rat heart: J.A. Hoerter, M.V. Miceli, G. Gerthenblith, D.G. Renlund, E.G. Lakatta and W.E. Jacobus. Johns Hopkins University, Div. Cardiology and Gerontology Res. Ctr., Baltimore, MD USA and U-241 INSERM, Orsay, France