Relation of free hydrogen sulfide concentration and relaxation in rat small arteries

Nitric Oxide ◽  
2015 ◽  
Vol 47 ◽  
pp. S56
Author(s):  
Elise R. Hedegaard ◽  
Anja Gouliaev ◽  
Mathilde Aalling ◽  
Nirthika Sivasubramaniam ◽  
Nini Skovgaard ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfide Concentration ◽  
Small Arteries ◽  
Free Hydrogen ◽  
Hydrogen Sulfide Concentration

Whole tissue hydrogen sulfide concentrations are orders of magnitude lower than presently accepted values

2008 ◽  
Vol 295 (5) ◽  
pp. R1479-R1485 ◽  
Author(s):  
Julie Furne ◽  
Aalia Saeed ◽  
Michael D. Levitt
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfide Concentration ◽  
Tissue Concentrations ◽  
Signaling Mechanism ◽  
High Hydrogen ◽  
Free Hydrogen ◽  
Gas Space ◽  
Hydrogen Sulfide Concentration

Hydrogen sulfide is gaining acceptance as an endogenously produced modulator of tissue function. The present paradigm of H2S (diprotonated, gaseous form of hydrogen sulfide) as a tissue messenger consists of H2S being released from the desulfhydration of l-cysteine at a rate sufficient to maintain whole tissue hydrogen sulfide concentrations of 30 μM to >100 μM, and these tissue concentrations serve a messenger function. Utilizing physiological concentrations of l-cysteine and aerobic conditions, we found that catabolism of hydrogen sulfide by mouse liver and brain homogenates exceeded the rate of enzymatic release of this compound such that measureable hydrogen sulfide release was less with tissue-containing vs. tissue-free buffers. Analyses of the gas space over rapidly homogenized mouse brain and liver indicated that in situ tissue hydrogen sulfide concentrations were only about 15 nM. Human alveolar air measurements indicated negligible free H2S concentrations in blood. We conclude rapid tissue catabolism of hydrogen sulfide maintains whole tissue brain and liver concentrations of free hydrogen sulfide that are three orders of magnitude less than conventionally accepted values and only 1/5,000 of the hydrogen sulfide concentration (100 μM) required to alter cellular function in vitro. For hydrogen sulfide to serve as an endogenously produced messenger, tissue production and catabolism must result in intracellular microenvironments with a sufficiently high hydrogen sulfide concentration to activate a local signaling mechanism, while whole tissue concentrations remain very low.

scholarly journals Effect of abiotic factors on sulfidogenic activity of bacteria Desulfuromonas sp.

2020 ◽  
Vol 11 (2) ◽  
pp. 170-174
Author(s):  
O. M. Сhaіka ◽  
T. B. Peretyatko
Keyword(s):  
Hydrogen Sulfide ◽  
Cell Density ◽  
Elemental Sulfur ◽  
Abiotic Factors ◽  
Electron Acceptors ◽  
Stress Factors ◽  
Sulfide Concentration ◽  
Sulfur Concentration ◽  
Reducing Bacteria ◽  
Hydrogen Sulfide Concentration

Sulfur-reducing bacteria are promising agents for the development of new methods of wastewater treatment with the removal of ions of heavy metals and organic compounds. Study of the effect of various environmental factors on the growth and sulfidogenic activity of sulfur-reducing bacteria allows one to investigate the adaptability of these microorganisms to stress factors. The paper deals with the effect of рН, different concentrations of elemental sulfur, hydrogen sulfide and presence of various electron acceptors on the growth and sulfidogenic activity of bacteria Desulfuromonas sp. YSDS-3. The calculation of C/S ratio for sulfur-reducing bacteria Desulfuromonas sp. YSDS-3 was made, with the comparison with similar parameters of sulfate-reducing bacteria. In the medium with elemental sulfur, concentration of hydrogen sulfide increased with the concentration of elemental sulfur. Bacteria Desulfuromonas sp. YSDS-3 accumulated their biomass in the most effective way at the concentration of elemental sulfur of 10–100 mM. In the medium with polysulfide form of sulfur at the neutral pH, bacteria produced hydrogen sulfide and accumulated biomass the best. Hydrogen sulfide at the concentration of 3 mM did not inhibit the bacterial growth, but further increase in the hydrogen sulfide concentration inhibited the growth of bacteria. The bacteria did not grow at the hydrogen sulfide concentration of 25 mM and above. As the concentration of elemental sulfur and cell density increases, sulfidogenic activity of the bacteria grows. Presence of two electron acceptors (S and K2Cr2O7, S and MnO2, S and Fe (III)) did not affect the accumulation of biomass of the bacteria Desulfuromonas sp. YSDS-3. However, under such conditions the bacteria accumulated 1.5–2.5 times less hydrogen sulfide than in the test medium. After 12–24 h of cultivation, different concentrations of elemental sulfur had a significant effect on the sulfidogenic activity. However, during 3–16 days of cultivation, the percentage of effect of elemental sulfur concentration decreased to 31%, while the percentage of effect of cell density increased threefold. Presence in the medium of the electron acceptors (Cr (VI), MnO2, Fe (III)) alternative to elemental sulfur led to a significant decrease in the content of hydrogen sulfide produced by sulfur-reducing bacteria.

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