Fig. 2.

(a) Example ³¹P spectrum acquired during baseline stability period showing normal cardiac energetics. (b) Time-series of ²³Na NMR spectra acquired in a perfused mouse heart during the infusion of Tm(DOTP) shift reagent. An initial shift of the intravascular extracellular signal [Na]_e is observed, followed by the signal from the buffer surrounding the heart [Na]_o was achieved within a 5–10 min timeframe.