Figure 4.

Quantification of the time course of AQP2 translocation to the apical plasma membrane of principal cells after VP/forskolin and SNP stimulation. The quantification of AQP2-membrane insertion was performed in the same way as described in Figure 2. AQP2 was distributed throughout the cytoplasm before addition of agonists, and this distribution was slightly (but not significantly) more pronounced after a further 15 minutes of in vitro incubation in the absence of agonists. A redistribution of AQP2 was already detectable 2 minutes after VP/forskolin or SNP addition and became progressively more marked after 5 and 10 minutes of treatment. After 15 minutes, the SNP effect was similar to the 10-minute response, while the effect of VP/forskolin was somewhat less pronounced after 15 minutes of treatment, although the difference was not statistically significant compared with the 10-minute time point. ^AP < 0.05 compared with control values (controls, both t = 0 and t = 15 minutes).