Effects of Na/K-ATPase knockdown on caveolae formation. Control or Na/K-ATPase knockdown cells were fixed and embedded, and ultrathin sections were analyzed by electron microscopy. Left: caveolae (A and insets b and c) were detected in the control cells as pointed by solid arrow, but rarely seen in the knockdown cells (C). Right: immuno-EM was performed to examine the localization of Cav1. Surface clusters of gold particles were detected in P-11 (B and inset d), but rarely seen in TCN23-19 cells (D). The number of caveolae or gold particles in each cell line was determined in images randomly acquired at the same magnification. Quantitative data were obtained by double-blind analysis in over 40 cells from each cell line, and listed in the table. A coated pit is pointed by an open arrow in A and inset “a”. Representative images are shown. Bar, 200 nm.