Evidence for the formation of a novel nitrosothiol from the gaseous mediators nitric oxide and hydrogen sulphide.
The gaseous mediators hydrogen sulphide (H2S) and nitric oxide (*NO) are synthesised in the body from L-cysteine and L-arginine, respectively. In the cardiovascular system, *NO is an important regulator of vascular tone and its over- or under-production has been linked to a variety of diseases. The physiological significance of H2S is not yet clear but, like *NO, it exhibits vasodilator activity and may play a part in septic and haemorrhagic shock, hypertension, regulation of cardiac contractility, and in inflammation. To date, there have been no reports of a chemical interaction between H2S and *NO. Here we show that incubation of the H2S donor, sodium hydrosulphide, with a range of *NO donors and *NO gas in vitro leads to the formation of a nitrosothiol molecule as determined by a combination of techniques; electron paramagnetic resonance, amperometry, and measurement of nitrite. We further show that this nitrosothiol did not induce cGMP accumulation in cultured RAW264.7 cells unless *NO was released with Cu2+. Finally, using liver homogenates from LPS treated rats we present evidence for the endogenous formation of this nitrosothiol. These findings provide the first evidence for the formation of a novel nitrosothiol generated by reaction between H2S and *NO. We propose that generation of this nitrosothiol in the body may regulate the physiological effects of both *NO and H2S.
Cardiovascular Biology Research Group, Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Republic of Singapore 117597. bchwm1@nus.edu.sg
Matthew
M
Whiteman
Ling
L
Li
Iouri
I
Kostetski
Siew Hwa
SH
Chu
Jia Ling
JL
Siau
Madhav
M
Bhatia
Philip K
PK
Moore
D000818:Animals; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D006862:Hydrogen Sulfide / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism*; D051381:Rats; D026403:S-Nitrosothiols / Q000378:metabolism*
D008070:Lipopolysaccharides; D026403:S-Nitrosothiols; D009569:Nitric Oxide; D006152:Cyclic GMP; D006862:Hydrogen Sulfide