Figure 5. Nephrin is transiently tyrosine phosphorylated during foot process effacement in the protamine sulfate–induced podocyte injury model.

Adult mouse kidneys were perfused as indicated prior to perfusion fixation with paraformaldehyde. Sections were analyzed by electron microscopy (top row; magnification, ×2,800) or by indirect immunofluorescence microscopy (bottom rows; magnification, ×400) after incubating sections simultaneously with rabbit P-nephrin or total nephrin antibody and with mouse anti-podocalyxin antibody. Protamine sulfate rapidly induced foot process effacement; normal podocyte morphology was nearly restored following perfusion with heparin sulfate. P-nephrin immunoreactivity was detected following protamine sulfate perfusion, but detection was attenuated following perfusion with heparin sulfate.