Fig. 1
From: Haptoglobin treatment prevents cell-free hemoglobin exacerbated mortality in experimental rat sepsis
Experimental setup and hemoglobin infusion protocol validation. a Setup scheme of the studies: a catheter was placed into the jugular vein and a telemetry ECG electrode was placed subcutaneously the day before the experiment. On the next day, the animals were randomized to a treatment group. Fecal slurry was injected i.p at T0h to induce sepsis. 4 h later, the animals were treated with ceftriaxone and a continuous saline infusion was started to provide fluid resuscitation. At the same time (T4h), we administered a bolus followed by continuous-rate infusion of saline, Hb or Hb–haptoglobin complexes for 24 h (Hb bolus = 16 mg, Hb continuous rate infusion = 15 mg/h, haptoglobin was dosed at an iso-stoichiometric concentration with Hb). b Besides the mortality study, we performed a separate study to determine plasma concentration of total Hb by spectrophotometry (left panel black symbols, indicated in heme equivalents), and plasma concentrations of CFHb, Hb–haptoglobin complex and hemoprotein by size-exclusion chromatography (gray symbols). Plasma was collected 3 h after starting the Hb or Hb–haptoglobin infusion (T7h). p values: * < 0.05, ** < 0.01, *** < 0.001, **** < 0.0001