Methanethiol metabolism in whole blood.

The metabolism of methanethiol in whole blood has been described. Incubation of carbon 14-labeled or sulfur 35-labeled gaseous methanethiol resulted in complete trapping of methanethiol by whole blood within 30 minutes. After trapping, both labels were found to be equally distributed over plasma and erythrocytes. Eighty to ninety percent of both labels could be extracted from erythrocytes incubated in saline solution. The chemical properties of the 14C and 35S labels in saline solution differed completely. The 14C label was not precipitated by BaCl2, was moderately volatile, and could be extracted by either (pH 1). In contrast, the 35S label was precipitated by BaCl2, was not volatile, and was not extracted by ether. It is concluded that the central carbon-sulfur bond of methanethiol is split by incubation with whole blood. Plasma components are not involved in this process. Most likely, methanethiol becomes largely oxidized by erythrocytes to formic acid and sulfite or sulfate. Only 10% of methanethiol became firmly bound to erythrocytes. One to two percent was transformed to protein--S--S--CH3 and 1% to dimethyl sulfide by the enzyme thiol methyltransferase.