Abstract
In various conditions, respiratory ^<14>CO_2 was determined after administration of ^<14>C-thiamine to rats and following results were obtained. 1. ^<14>CO_2 was excreted in the expiration rapidly within 6 hours after ^<14>C-thiamine administration and then slowly excreted until 24 hours. However, after 24 hours expired ^<14>CO_2 was not detected. 2. Linear relationship was observed between expired ^<14>CO_2 and amounts of injected ^<14>C-thiamine up to 100μg of administered ^<14>C-thiamine per 100g of body weight of rats. When administered ^<14>C-thiamine exceed 100μg per 100g of body weight, ratio of ^<14>CO_2 to administered ^<14>C-thiamine was decreased. 3. Amounts of expired ^<14>CO_2 per body weight was constant when fixed amounts of ^<14>C-thiamine per body weight was administered to rats.
