Fig. 5.

Adaptation of glutamine transporter and ammoniagenic enzymes in the kidney cortex of rats treated with acetazolamide (ACTZ) or NH₄Cl loading for 2 wk. A and D: tissue homogenates (enzymes) and membrane fractions (SNAT3) were isolated from the kidney cortex of rats treated with NH₄Cl loading (A) or ACTZ (D) versus their respective control or vehicle treatment and were used for immunoblot analysis using specific antibodies for each protein. B, C, E, and F: corresponding average means ± SE of the densitometry analysis of SNAT3 (B and E) and ammoniagenic enzymes (C and F) in response to NH₄Cl loading versus control (B and C) or in ACTZ-treated versus vehicle-treated rats (E and F). The abundance of these proteins was normalized to actin used for the control of gel loading. As shown, SNAT3 was sharply upregulated in NH₄Cl-loaded rats but not ACTZ-treated rats for 2 wk. Phosphate-dependent glutaminase (PGA) and glutamate dehydrogenase (GDH) were slightly, but significantly, upregulated in ACTZ-treated rats for 2 wk. The magnitude of PGA induction was greater in NH₄Cl loading versus ACTZ treatment. n = 5 rats in each group. Each lane was loaded with 10−30 μg protein from the kidney cortex. Note that the exposure time for SNAT3 in vehicle versus ACTZ (D) was much higher than that in control versus 6 days of NH₄Cl loading (A). GS, glutamine synthetase; NS, not significant.