Figure.

Panel A. Original recording of the changes in arterial blood pressure, cardiac output and the left ventricular pressure, during H₂S infusion in a 500 g rat receiving a solution of sulfide made from NaHS (1 mg/min). There was a rapid decrease in cardiac output, arterial pressure and left ventricular pressure, which led to asystole, within 5 minutes. The horizontal bracket shows the period at which of cardiac output was determined for the computations shown in B. Panel B. V̇O₂ (left panel) and the change in O₂ extraction as % from baseline (Right panel) as a function of cardiac output. 10 second-averaged data obtained from 7 rats during the first minutes of an infusion of H2S at toxic levels (2 mg/min) are shown. Cardiac output dropped dramatically, while oxygen extraction increases reflecting a proportionally higher fall in O₂ delivery than in O₂ utilization. Note that PaO₂ and thus the arterial O₂ content was prevented to decrease by mechanical ventilation throughout the period of infusion.