The absorption of pteroylpolyglutamate and intestinal pteroylpolygammaglutamyl hydrolase activity in zinc-deficient rats.

The effect of dietary zinc deficiency on pteroylpolygammaglutamyl hydrolase (folate hydrolase) activity and on pteroylpolyglutamate absorption was studied in rats. Three groups of male Sprague-Dawley rats (zinc-deficient, restricted-fed and ad libitum-fed controls) were fed a semipurified 25% egg white protein diet. The zinc-deficient group received 0.7 mg zinc/kg diet, whereas restricted-fed and ad libitum-fed control groups received 106 mg zinc/kg diet. After 6 wk of feeding, intestinal mucosal folate hydrolase activity was determined, and the absorption of pteryl-U[14C]glutamylhexaglutamic acid [(14C]PteGlu7) and [3H]pteroylglutamic acid [(3H]PteGlu) was measured after intragastric administration. The intestinal mucosal folate hydrolase activity of zinc-deficient rats was not significantly reduced compared with two control groups. No significant differences in the absorption of [14C]PteGlu7 and [3H]PteGlu were found among the three groups. These results indicate that intestinal folate hydrolase is not zinc dependent in rats and the intestinal absorption of pteroylpolyglutamate is not reduced in zinc-deficient rats.