RESUMO
Levels of thiamin and its derivatives in brain, heart and liver were determined in control, thiamin-deficient, pyrithiamin-treated and oxythiamin-treated rats at various times after the start of treatment. With 10 micrograms of thiamin/100 g/day subcutaneously, rats rapidly lost thiamin from the tissues until growth maintenance levels were reached. Oxythiamin had a minimal further effect on tissue thiamin while pyrithiamin caused further marked reduction. With higher levels of thiamin intake, tissue thiamin levels increased with intakes of up to 150-200 micrograms/100 g/day after which they did not show any further significant increase. Levels of pyrithiamin above 50 microgram/100 g/day for 20 days had only minimal further effect upon tissue thiamin levels over that with 50 micrograms.