Fig. 4.

Labeling after Ang II stimulation. GST-PH was applied at a concentration of 100 ng/mL. (A) Representative micrographs of the PI(4,5)P₂ labeling before and 10, 40, and 130 sec after the treatment with 1 μM Ang II. (B) The time course of the labeling intensity change. The relative labeling intensity was shown by taking the labeling density of the control sample as the standard (the average ± standard deviation; **, P < 0.001). Thirty areas of the undifferentiated membrane and 30 caveolae were randomly chosen for each time point. For caveolae, the labeling at 30–50 nm from the center was measured. (C) The labeling intensity in relation to the distance from the caveolar center. The labeling density in the undifferentiated membrane of the untreated cell was taken as the standard. Thirty caveolae were randomly chosen for each time point. The labeling at 30–50 nm from the caveolar center did not change significantly at 5 sec and 10 sec after the Ang II stimulation. At 40 sec, the caveolar labeling decreased significantly, whereas the labeling in the flat membrane started to recover and was denser than that of the caveolar rim. The caveolar labeling returned to the control level at 130 sec.