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Quantification of Sulfide in the Human Cutaneous Microcirculation Bioassay: Methylene Blue Assay Versus an Amperometric Sensor
Author(s) -
Shank Sean,
Alexander Lacy,
Castro Rita
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.lb764
Subject(s) - methylene blue , amperometry , microdialysis , chemistry , hydrogen sulfide , in vivo , sulfide , vascular smooth muscle , nuclear chemistry , chromatography , biophysics , biochemistry , extracellular , medicine , electrochemistry , organic chemistry , sulfur , smooth muscle , biology , catalysis , microbiology and biotechnology , electrode , photocatalysis
Impaired microvascular function, characterized by attenuated nitricoxide (NO)‐mediated endothelium‐dependent dilation, is one of the earliestmanifestations of cardiovascular disease, and occurs prior to dysfunction inconduit arteries and veins. In addition to NO, hydrogen sulfide (H 2 S)is an important signaling molecule involved in the regulation of vascular tone throughits direct effects on vascular endothelial and smooth muscle cells, andindirect effects by interacting with the NO‐synthase signaling pathway. Atphysiologic pH, H 2 S is easily lost by dissipation into theatmosphere, making it difficult to reliably quantify in biological samples. Thepurpose of this experiment was to compare methods for quantifying H 2 Sconcentration in our in vivo bioassayexamining H 2 S‐dependent mechanisms in the human cutaneousmicrovasculature. We compared a sulfide‐sensitive amperometric sensor to amethylene blue assay to measure sulfide concentration in dialysate obtained fromintradermal microdialysis probes. We hypothesized that the methylene blue assaywould be more accurate than the amperometric sensor in quantifying H 2 Sconcentration because the former uses zinc acetate, which traps the H 2 Sin solution, preventing dissipation to the atmosphere. To test this we perfusedtwo different concentrations of Na 2 S (20 and 60 mM), a H 2 Sdonor, through four intradermal microdialysis fibers placed into the ventralforearm. Dialysate from the probes was collected in either phosphate‐bufferedsaline or in zinc acetate (1%) solution for immediate H 2 Squantification. The ratio between the sulfide content pre‐to‐post dialysis was quantified in one set of samples using the amperometric probe and in a second set of samples by methylene blue assay. Using the methylene blue assay, the sulfide ratios were 0.94 ± 0.06 and 0.91 ± 0.18 for 20 and 60 mM Na 2 S, respectively. Using the amperometric sensor, the ratios were 0.69 ± 0.16 and 0.74 ± 0.14 for 20 and 60 mM Na 2 S, respectively. We concluded thatthe methylene blue assay is a more accurate method to quantify H 2 Sconcentration in dialysate from intradermal microdialysis fibers. Therefore, amethylene blue assay may be a better method to quantify H 2 S concentration in microdialysis dialysate samples. Support or Funding Information NIH HL093238 (LMA)