Thiamin transport by rat small intestine "in vitro": influence of endogenous thiamin content of jejunal tissue.

The relationship between thiamin intestinal transport and phosphorylation in vitro was investigated using everted jejunal sacs from normal rats, rats affected with dietary thiamin deficiency at different degrees and relative pair-fed controls; recovered rats, i.e. severely thiamin-deficient animals, 6 hours after the intravenous injection of 1 mg of thiamin chloride/100 g body weight.

Subcellular distribution of thiamine-pyrophosphokinase and thiamine-pyrophosphatase activities in rat isolated enterocytes.

Starting from mucosal cells, isolated from rat small intestine, subcellular fractionation was carried out. Four fractions were prepared and characterized by marker enzymes and electron microscopic examination: nuclei plus microvilli, mitochondria, microsomes and supernatant. Thiamine-pyrophosphokinase activity was localized mainly in the supernatant fraction, with minor amount in mitchondria and microsomes.