Sulphur metabolism. IV. The oxidation and reduction of elementary sulphur by animal tissues in vitro

Abstract

1. Data are presented on the oxidation and reduction of elementary sulphur by animal tissues in vitro, and the enhancing or otherwise effects of certain chemicals on these reactions are also shown. 2. All protein tissues seem to be capable of reducing sulphur to H₂S. Acid (HCl) inhibits this reaction whereas alkalies and alkaline salts enhance it. 3. Similarly, acid inhibits and alkalies and alkaline buffers increase the oxidation of reduced sulphur to sulphate. An alkaline medium, rich in oxygen, is therefore essential for the oxidation and detoxication of H₂S. This is readily accomplished in blood where these conditions are excellently fulfilled. Nevertheless, all tissues in the animal organism should be able to oxidize sulphides, in view of the fact that oxygen (e.g. H₂O₂) and phosphates (buffers) are present in all tissues. 4. The chief, if not the sole, effect of alkali on the oxidation of sulphur seems to be to bind and concentrate the reduced sulphur in the solution where it is then oxidized to sulphate by the oxygen present in the corpuscles, in the case of blood, or by atmospheric oxygen, in the case of other tissues. Furthermore, the oxidation of sulphur by tissues under laboratory conditions is not influenced by enzyme activity, in view of the fact that no difference was found in the oxidation of H₂S by fresh, boiled or dried tissue suspensions in an alkaline (Na₂CO₃) thymol-Ringer solution. As a matter of fact the oxidation of H₂S also took place with relative ease in alkaline (and buffer) solutions without the presence of tissues. 5. Similarly, the reduction of sulphur by animal tissues is not due to enzyme activity because the reaction took place in tissues that were boiled previous to their incubation with sulphur in a very strong antiseptic solution. 6. A dose parallelism was found to exist, under laboratory conditions, between the increases in the oxidation of sulphur and (as a result of) the different percentages (on the dry basis) of modified Steenbock salts 40 added to the intestinal contents of the rats fed an ash and protein-free ration. This suggests that a diet with an excess of base-forming elements may be of importance in the oxidation and detoxication of sulphides in cases where large amounts of H₂S are formed in the digestive tract. 7. The possibility of beneficial effects arising from injecting (subcutaneously or intramuscularly) a colloidal suspension of sulphur in an alkaline solution as an antidote in certain cases of acute poisoning is discussed.