Figure 1.

(A,B) In vivo calibration curve of SNARF-AM. To determine calibration curve myocytes were loaded with SNARF-AM and superfused in presence op nigericin with several high K⁺ solutions at various pH_o values (A). When the external and internal K⁺ free concentrations are equal, pH_i is the same as pH_o. The calibration curve (B) was obtained by plotting the ratios (580/640) against the corresponding pH_o. The red line represents a Henderson–Hasselbalch fit through these data, which revealed a maximum ratio of 2.97 and a minimum ratio of 0.36 and a pK_a of 7.57. (C,D) Determination of the intrinsic sarcoplasmic buffer power (β_i). Typical example of the “stepwise reduction in extracellular NH₃/NH₄⁺ approach” in a myocyte isolated from a healthy, ω3-PUFA fed animal (C), and pH_i–βⁱ relationships of ω3-PUFA and ω9-MUFA myocytes of both healthy rabbits (Ctrl) and the rabbits with heart failure (HF). (E) Typical example and schematic explanation of an ammonium prepulse. (F) Typical examples of effects of Na⁺-free conditions and cariporide on the acid load recovery in HEPES-buffered conditions.