[Effect of amines on the pH in the lysosomes of 3T3 cells]

The measurements of intralysosomal pH under the action of the number of amines earlier reported to block the process of the initiation of cell proliferation (Nikolsky et al., 1984) were made on Swiss 3T3 cells. The intralysosomal pH (pH1) value was estimated by parameters of fluorescence of fluorescein-labeled dextran in single intact cells. The pHl value was equal to 4.7 +/- 0.2 for both actively growing and quiescent cells. The pH gradient between lysosomes and the cytoplasm was completely destroyed by monensin and partially by carbonylcyamide-m-chlorophenylhydrasone. Methylamine and chloroquine rapidly enhanced the pHl, value to 6.4-7.0. Dansylcadaverine, 5-methoxytryptamine and dimethylurea did not affect pHl value. Intracellular accumulation of dansylcadaverine was shown to be due to the existence of acidic compartments into the cell and highly decreased in the presence of monensin. A conclusion is made that the inhibition of mitogenic signal by amines cannot be unequivocally accounted for by increasing the pH in organelles involved in the intracellular processing of growth factors.