Figure 4.

Endothelial cilia respond to a specific range of fluid shear stresses. A, Immunostaining studies show colocalization of polycystin-1 (PC1; green) and polaris (red) counterstained with nuclear marker DAPI (blue). Note that polycystin-1 appears to be concentrated in the basal body of the Tg737 mutant cells. Bar=5 μm. n = 4. B, All cells were first exposed to a fluid shear stress of 0, 1.1, or 7.2 dynes/cm² for 30 minutes, followed by the corresponding step increase in shear stress as depicted in the graphs. Cytosolic calcium ([Ca²⁺]_cyt) was measured as a readout in response to fluid shear stress. Although wild-type cells respond to a range of shear stress, neither mutant cell shows any apparent response to different magnitudes of shear stress. n = 3 to 6 for each time point in a given shear stress condition. C, Cumulative measurements of cytosolic NO biosynthesis ([NO]_cyt) at the predicted optimal ranges of shear stress. n = 3 to 6 for each time point in a given shear stress condition.