Changes in cellular oxygenation, redox status, and cardiac function of left ventricular working hearts when perfusate was transitioned from Krebs-Henseleit (KH) to perfluorocarbon (PFC) and back to KH. A−D: average changes in myoglobin (A), cytochrome a605 (B), heart rate (C), and cardiac output (D) during KH perfusion, PFC perfusion, and KH perfusion after PFC perfusion. Data represent means ± SE; n = 4 for spectral data (A and B) and n = 6 for functional data (C and D). *Significantly different from baseline with KH.