Zinc uptake by basolateral membrane vesicles from rat small intestine.

Zinc uptake (transport and binding) by basolateral membrane vesicles was investigated using membranes derived from small intestines of rats fed zinc-adequate and zinc-deficient diets. Uptake was separated into saturable and nonsaturable (diffusion) components. Kinetic analysis of initial rates of the saturable component of uptake (at 1 min) indicates half maximal uptake (Km) by vesicles from zinc-adequate rats was observed at a medium Zn2+ concentration of 24 microM. The maximum Zn2+ uptake rate (Jmax) of the saturable component was 17 nmol/(mg protein.min). Dietary zinc intake did not affect these parameters. Zn2+ transport by the basolateral membrane may involve an ATP-driven mechanism.