FIGURE 7.

Rate of endocytosis of NHE3 in response to PTH is not significantly different between scrambled and ClC-5 silenced cells. OK cells transfected with sc or sh constructs were incubated at 37 °C in the presence of PTH (0.5 μm) for 0, 20, 35, and 50 min. The amount of endocytosis of NHE3 (internalization of surface NHE3) at the above indicated time points was determined by a GSH-resistant endocytosis assay as described under “Experimental Procedures.” A, a representative blot from three independent experiments is shown. B, quantitative analysis of endocytosis of NHE3 by densitometry from experiments described in A. The amount of internalized NHE3 via endocytosis at each time point (20, 35, and 50 min) was calculated as the percentage of surface NHE3 of the corresponding control group, which was always kept at 4 °C and was not exposed to GSH. The slopes of endocytosis of NHE3 were calculated to determine the rates of endocytosis in sc and sh groups as shown in A. Results are mean ± S.E. of data from three independent experiments. Con, control.