Fig. 4.

Comparison of PM SERT expression on freshly isolated trophoblast from normal and GDM placentas. (A) Trophoblast were prepared from normal (N) and GDM placentas. PM expression of SERT was determined by flow cytometry (75, 76). Mean fluorescence intensity of SERT expression in trophoblast (5 × 10⁴ per assay) isolated from normal placentas (red histogram) was higher than in trophoblast from GDM placentas (blue histogram), black histogram represents negative control. Flow cytometry revealed a decrease of 51% in the expression levels of SERT in trophoblast of GDM placentas. Asterisk, statistical difference between normal and GDM trophoblast. (B) For quantification of SERT on the PM, trophoblast (1.5 × 10⁶ per biotinylation assay) cells were treated with sulfo-NHS-SS-biotin as described (37, 39, 68). The WB analysis of the biotin labeled PM proteins was performed with anti-SERT or Na⁺/K⁺-ATPase Abs (locates PM proteins). All lanes contain protein recovered from the same number of cells (1.5 × 10⁶ per assay). The band densities were calculated as the ratio of each band to the level of actin. Averaged data from three independent experiments are presented ± SE. The values are statistically different (P < 0.001, Student t test).