Table 1 Do NO, CO and H2S qualify as gasotransmitters?

For criteria (iv) to (vi), examples are given.

CriterionNOCOH2S
(i) Small gas
(ii) Membrane-permeable
(iii) Endogenously synthesised
(iv) Specific functions; manipulating endogenous levels evokes changes✓ antibiotic resistance, virulence, quorum sensing, biofilms, etc.unclear, except in CO metabolism1✓ antibiotic resistance, oxidative stress resistance
(v) Effects mimicked by exogenous counterpartsOnly toxicity can be mimicked by CO or CORMs?
(vi) Specific cellular/molecular targets2unclearOnly via persulfide chemistry
  • 1 We do not regard use of CO as a metabolic substrate as signal transduction or gasotransmitter functions; endogenous CO is not used in this way.

  • 2 We exclude targets such as metal centres that may lead to toxicity.