Transport of thiamine into red blood cells of the rat.

Thiamine transport by the red blood cells of rats was investigated at a physiological concentration of thiamine. The transport rate became large in accordance with the decrease of the initial thiamine concentra tion in the medium. Pyrithiamine and chloroethylthiamine inhibited this transport but oxythiamine did not. The examination of counter flow showed that thiamine efflux from the red blood cells after preload ing was accelerated by thiamine added in the medium. However, the metabolic energy was not required for the thiamine transport by the red blood cells. This evidence indicates that thiamine is taken up by facilitated diffusion by the red blood cells of rats at a physiological concentration of thiamine.