In this study, we have tried to characterize the limits of the approach typically used to determine H2S concentrations in the heart based on the amount of H2S evaporating from heart homogenates - spontaneously, after reaction with a strong reducing agent or in a very acidic solution. Heart homogenates were prepared from male rats in control conditions, following H2S infusion induced a transient cardiogenic shock (CS) or cardiac asystole (CA). Using a method of determination of gaseous H2S with a detection limit of 0.2 nanomoles, we found that the process of homogenization could lead to a total disappearance of free H2S unless performed in alkaline conditions. Yet, after restoring neutral pH, free H2S concentration from samples processed in alkaline and non-alkaline milieu were similar and averaged ~ 0.2-0.4 nmol/g in both control and CS homogenate hearts and up to 100 nmol/g In the CA group. No additional H2S was released from control, CS or CA hearts, using the reducing agent TCEP or a strong acidic solution (pH < 2) in order to "free" H2S from combined pools. Of note, the reducing agent DTT produced a significant sulfide artifact and was not used. These data suggest that 1- free H2S found in heart homogenates is not a reflection of H2S present in a "living" heart 2- The pool of combined sulfides, released in a strong reducing or acidic milieu, does not increase in the heart in a measurable manner even after toxic exposure to sulfide.
- H2S cardiotoxicity
- sulfide metabolism
- H2S intoxication
- Copyright © 2016, American Journal of Physiology-Heart and Circulatory Physiology