Absorption and Excretion of Drugs. XXXVII. Effect of Ca²⁺ on the Absorption of Tetracycline from the Small Intestine. (2)

Urinary excretion of tetracycline tended to increase in the presence of EDTA. Experiments employing Wiseman's apparatus showed the accumulation of tetracycline in an intestinal membrane. Examination of fluorescence under a black lamp made possible to visualize the binding of tetracycline to mucosa both in vitro and in vivo. Using villi preparation from rat intestine the binding of tetracycline to villi in the presence of Ca2+ was demonstrated in a binding study, a distribution study, and a dialysis study. EDTA was found to release free tetracycline from villi-bound tetracycline both in vitro study using a villi preparation and in vivo study in man.