Fig. 5.

Influence of Hsc70 on rate of ENaC retrieval from the apical cell surface. MDCK cells were treated without or with Dox for 24 h, and a baseline I_sc was established in Ussing chambers. Cycloheximide (100 μg/ml) was added, and amiloride-sensitive I_sc was determined at the indicated times. Values are means ± SE for n repeats. Pseudo-1st-order rate constants (k_app) for decay of amiloride-sensitive I_sc were determined by fitting these data to the following equation: (I_t/I₀) = e^−kt, where (I_t/I₀) is the fraction of ENaC current remaining at time t and k (k_app) is the apparent 1st-order rate constant, by a nonlinear regression using the Regression Wizard function of Sigma Plot (version 8.0). This analysis yields k_app ± SE, which were then compared by t-test as a function of ± Dox. A: cells expressing Hsc70. B: cells expressing ATPase-deficient Hsc70.