Growth inhibition of 3T3 fibroblasts by lysosomotropic amines: correlation with effects on intravesicular pH but not vacuolation.

The effects of five lysosomotropic amines on the growth of Swiss 3T3 fibroblasts were measured and compared with effects on intravesicular pH. Tributylamine and benzylamine, amines that affect intravesicular pH without causing vacuolation, were found to inhibit cell growth to a similar extent as vacuologenic amines previously tested. Excellent correlation between the half-maximal concentrations for the growth and pH effects were found for tributylamine, benzylamine, chloroquine, and ammonium chloride. The results suggest that growth inhibition by these amines is a direct result of their effects on pH and not due to other effects (such as vacuolation). In contrast, a 100-fold difference in the half-maximal concentrations was found for methylamine, suggesting that methylamine inhibits growth by a mechanism unrelated to pH.