The Effects of Inhibitors of Microtubule and Microfilament Function on Transferrin and Iron Uptake by Rabbit Reticulocytes and Bone Marrow

S ummary . The possible involvement of microtubules and microfilaments in the uptake of transferrin and iron by rabbit reticulocytes and bone marrow cells was investigated by using agents which interfere with the functions of these cellular components. Colchicine, vinblastine, vincristine, strychnine, and heavy water, which inhibit microtubule function, all diminished transferrin and iron uptake by the cells. Vinblastine was also shown to inhibit transferrin release fiom reticulocytes and the uptake of both citrate‐bound iron and leucine. Cellular ATP levels were not affected. Cytochalasin B which is believed to disrupt microfilaments did not affect transferrin or iron uptake by the cells. It is concluded that the inhibitory effects observed were due to alteration of structural components of the cell membranes, probably in the microtubules.