Table I.

Rate and extent of lysosome re-acidification after cytosolic anion dialysis and protonophore-induced alkalinization

 n τ (min) pHf − pHo pHalk − pHf 
Control 16 0.68 ± 0.07 −0.01 ± 0.03 0.91 ± 0.09 
Gluconate 0.44 ± 0.02 −0.03 ± 0.03 0.72 ± 0.17 
  (P > 0.05; NS) (P > 0.05; NS) (P > 0.05; NS) 
MeSO4 0.69 ± 0.06 0.09 ± 0.05 1.31 ± 0.05 
  (P > 0.05; NS) (P > 0.05; NS) (P < 0.05) 
CFTRINH-172 1.34 ± 0.25 −0.17 ± 0.10 0.71 ± 0.07 
  (P < 0.01) (P > 0.05; NS) (P > 0.05; NS) 
 n τ (min) pHf − pHo pHalk − pHf 
Control 16 0.68 ± 0.07 −0.01 ± 0.03 0.91 ± 0.09 
Gluconate 0.44 ± 0.02 −0.03 ± 0.03 0.72 ± 0.17 
  (P > 0.05; NS) (P > 0.05; NS) (P > 0.05; NS) 
MeSO4 0.69 ± 0.06 0.09 ± 0.05 1.31 ± 0.05 
  (P > 0.05; NS) (P > 0.05; NS) (P < 0.05) 
CFTRINH-172 1.34 ± 0.25 −0.17 ± 0.10 0.71 ± 0.07 
  (P < 0.01) (P > 0.05; NS) (P > 0.05; NS) 

The differences between the initial lysosome pH (pHo; step I of the protocol shown in Fig. 3 A), pH after protonophore-induced alkalinization (pHalk; step II of the protocol in Fig. 3 A), and final pH after re-acidification (pHf; step III of the protocol in Fig. 3 A) were calculated. To determine the half-life of the pH decay (τ) the data for lysosome re-acidification after protonophore washout were fit to a single exponential of the form y = A * exp(−K x) + B and τ calculated as 0.69/K. All values are listed as mean ± SE. The p-values, given in parentheses, were determined by ANOVA using Dunnett’s test for multiple comparison to the control (NS, not significant). n refers to the number of experiments performed for each condition. For each experiment, 6–13 regions of interest were measured.

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