Disappearance from blood and urinary excretion of 35S-thiamin in sheep. A kinetic study.

In seven experiments with two adult sheep a single dose of 35S-thiamin was injected intravenously. Blood and urine samples were taken at short intervals after dosing and analyzed for 35S-radioactivity. The data obtained were subjected to a curve fitting computer program. The disappearance of 35S-thiamin from blood followed a three-exponential function; the average half-times of the three components were 0.4, 3.7 and 93.7 minutes. Urinary excretion of the tracer was also three-exponential and amounted to 19--32% of the injected dose over 150 minutes.