Figure 5.

Temporal profile of the changes (mean ± SD) in left ventricle ejection fraction (EF) and cardiac output (A), expired H₂S, blood pressure, $\dot{V}$O₂ and $\dot{V}$CO₂ (B) following sulfide exposure in protocol 2 (sublethal intoxication). The closed symbols represent the untreated animals while the open symbols represent the animals treated by MB (3 min after the end of sulfide exposure) whereas the red-dotted line corresponds to the average data of the untreated animals. Note the drop in EF during H₂S exposure in both groups and that in the nontreated animals, a continuous decrease in EF developed over time reaching −50% of the baseline value at 30 min along with a significant reduction in cardiac output. MB in all instance restored the cardiac function. Also note that (1) H₂S in expired gas was undetectable, when MB was administered, (2) blood pressure was not different between the 2 groups of animals, reflecting a rise in peripheral vascular resistance in the non-treated sheep, and (3) O₂ consumption and CO₂ production increased in response to MB (see text for discussion). C, PL ratio also increased after MB and returned to baseline values. Concentrations of MB decreased form 121 μM at 1 min to 20 μM at 30 min.