INFLUENCE OF ASCORBIC-ACID, SODIUM-CITRATE, AND SODIUM-BICARBONATE ONTHE UPTAKE OF FE-59-TRANSFERRIN, MN-54-TRANSFERRIN, AND ZN-65-TRANSFERRIN FROM LACTATING MOUSE MAMMARY-GLAND CELLS

The effects of ascorbic acid, sodium citrate, and sodium bicarbonate o n Fe-59-transferrin, Mn-54-transferrin, and Zn-65-transferrin uptake b y the receptors disposed of plasma membrane isolated from lactating mo use mammary gland cells have been investigated. The effect of 10(-2) m ol/L ascorbic acid alone and in combination with NaHCO3 on the Fe-59-t ransferrin uptake is significant and positive. 54Mn-transferrin and 65 Zn-transferrin binding to the cell receptors are influenced optimally by 0.5 mol/L sodium bicarbonate. Sodium citrate alone or in combinatio n with other substances always has a negative effect on binding of the se three metals. It is suggested that a precise mechanism may exist wi th large possibilities to rearrange metal uptake and its transport fro m blood to milk