Figure 7.

Effect of proximal tubule (PT)-specific Na⁺-bicarbonate cotransporter, electrogenic, isoform 1 (NBCe1) deletion [PT-NBCe1-A/B knockout (KO)] on glutamine synthetase (GS) expression under basal conditions and after acid loading. A: immunoblot analysis of the renal cortex and outer stripe of the outer medulla (OSOM) on both the basal diet and after the acid-loading diet. B: quantification of results from the cortex. NBCe1-A/B deletion increased GS expression significantly in the cortex while on the basal diet. Acid loading decreased GS expression significantly in wild-type (WT) mice but not in KO mice, and expression was significantly greater in acid-loaded KO mice than in acid-loaded WT mice. C: quantification of results from the OSOM. Total GS expression was significantly greater in KO mice than in WT mice on the basal diet. Acid loading decreased GS expression in WT mice but not in KO mice, and expression was significantly greater in acid-loaded KO mice than in acid-loaded WT mice. Immunoblot analysis results are representative of findings in n = 4 male (M)/3 female (F) mice for each genotype on the basal diet and 6M/3F WT mice and 4M/3F KO mice on the acid-loading diet. Statistical analysis used ANOVA with genotype, diet, and sex as independent variables. Sex did not significantly alter the effects of genotype in the cortex. Effects of sex in the OSOM are detailed in the text. P values show results of specific unpaired t test comparisons. NS, not significant.