Blockade of the Na+/H+ antiport abolishes growth factor-induced DNA synthesis in fibroblasts. Structure-activity relationships in the amiloride series.

摘要: We have previously characterized in Chinese hamster lung fibroblasts a growth factor activatable and amiloride-sensitive Na+/H+ antiport (Pouyssegur, J., Chambard, J. C., Franchi, A., Paris, S., Van Obberghen-Schilling, E. (1982) Proc. Natl. Acad. Sci. U. S. A. 79, 3935-3939). In this report, we compared the affinity of 28 analogs amiloride for inhibition factor-induced DNA synthesis. showed that guanidino moiety must be protonated to elicit exchange. Substitutions within by methyl, phenyl, or benzyl groups reduced activity 20- 1000-fold. On contrary, substitution proton(s) 5-amino group with alkyl alkenyl increases potency up 100-fold (5-N,N-diethylamiloride has KI 4 X 10(-8) M). HCO-3-free medium at lower [Na+]0 (25 50 mM) reduce competition amiloride, found factor-stimulated synthesis G0-arrested cells is inhibited its same rank order as antiporter inhibition. Over range 3 logs concentration, tight correlation was established between IC50 blockade both processes, exchange percentage entering S phase upon action. These findings indicate that, medium, functioning system required