Cultures maintained in NGF, deprived of NGF, or deprived of NGF for 24 hr and exposed to medium containing CHX (1 μg/ml), BAF (30 μm), or l-NAC (30 mm) were loaded with BCECF in the treatment medium. They were then placed in L-15 medium, containing the appropriate treatment, for 490:440 ratio determinations. Cultures treated with antimycin A (1 μm), FCCP (5 μm), or rotenone (10 μm) were deprived of NGF for 24 hr and exposed to the compounds only during BCECF loading and during recording. This acute treatment was done because of potent suppression of protein synthesis by these compounds with long-term treatment (Table 2). Lower 490:440 ratios indicate acidification. Asterisk denotes significantly different values (p < 0.01) from average control values measured in sibling NGF-maintained cells at the same time. All statistical comparisons were made by Mann–Whitney rank sum test. N= 37–59 cells from two or three separate platings except for the 3–24 hr time course in which N = 35–36 cells from two platings. The range of 490:440 ratios measured in NGF-maintained cells is shown at top.