Comparison of the effects of nitrogen mustard on the functional properties of mitochondria from sensitive and resistant strains of Ehrlich ascites tumors.

In vivo treatment of sensitive tumor cells with nitrogen mustard (HN2) results in marked inhibitions of protein and nucleic acid synthesis by mitochondria subsequently isolated from these cells. This inhibition occurs at doses of drug which produce no apparent inhibition of total RNA synthesis. The inhibition gradually reverses itself in sensitive cells and is less severe and more rapidly reversed in resistant cells. The in vivo sensitivity of the mitochondria is in striking contrast to their in vitro behavior; isolated mitochondria resist 50 times the in vivo ID50 level of the drug. The sensitivity of protein and RNA synthesis in mitochondria is presumed to be related to the differences in organization between the nucleocytoplasmic processes and the mitochondrial. But the data also suggest that the in vivo effects on mitochondria are indirect, either acting via the cytoplasm or nucleus or via a carrier mechanism having mitochondrial affinity.