An autoradiographic study of the binding of 3-H-chlorambucil to cells of a drug-sensitive and drug-resistant strain of the Yoshida ascites sarcoma.

The binding of chlorambucil to drug-sensitive and drug-resistant. Yoshida sarcoma cells has been investigated by an autoradiographic technique. The cells were treated with the drug at various concentrations both in vitro and in vivo. Using both light and electron microscope techniques, and by counting grains on various areas of the cell, the following conclusions were reached. (1) At all drug concentrations there was general cytoplasmic and nuclear uptake by both cell lines. There was no evidence of a specific localization in one site only or for specific exclusion of any one site. (2) At high dose levels (equivalent to 2 mM) the binding was approximately equal in both cell lines, although a few damaged cells bound much greater amounts of drug. (3) At low dose levels (equivalent to 3 mu-M) there was a higher uptake by the nucleus of the sensitive cells compared with the nucleus of the resistant cells; the cytoplasmic binding was similar.