Ion permeability induction by the SH cross-linking reagents in rat liver mitochondria is inhibited by the free radical scavenger, butylhydroxytoluene.

The hydrophobic, potentially SH cross-linking reagent, phenylarsine oxide (PhAsO), was found to induce K+ and Ca2+ effluxes from mitochondria and to accelerate the respiration rate in state 4. The hydrophobic monofunctional electrophilic agent, N-ethylmaleimide, does not exhibit this effect but prevents the action of PhAsO. The polar potentially SH cross-linking regents (arsenite, diamide) induce ion fluxes only in the presence of Pi. Ion fluxes induced by the SH reagents are inhibited by butylhydroxytoluene (an inhibitor of free radical reactions), and N,N'-dicyclohexylcarbodiimide, not by oligomycin. It is inferred that the induction of ion fluxes in mitochondria caused by cross-linking of two juxtaposed SH groups is related to the development of free radical reactions.