Fig. 6.

AMPK activation inhibits CRT-mediated [¹⁴C]creatine uptake in mouse S3 proximal tubule cells. Polarized mouse proximal tubule S3 segment cells were grown on Transwell filters. A: relative AMPK activity as measured by phosphorylated (Thr¹⁷²) AMPK-α immunoblotting following treatment with AICAR (1 mM, 2 h) vs. vehicle. Values are means ± SE. *P < 0.05 (n = 3). B: relative CRT uptake assays. Krebs-Ringer-HEPES buffer was applied in the presence or absence of AICAR containing 10 μM [¹⁴C]creatine on the apical side for 45 min at 37°C (n = 3 per condition). The competitive CRT substrate β-guanidinopropionic acid (1 mM) was added in parallel CRT uptake flux measurements as a control (not shown). Resulting non-CRT-mediated [¹⁴C]creatine uptake (generally ∼10% of total) was considered background, and this value was subtracted from total uptake values. AICAR induced a ∼20% inhibition in CRT-dependent [¹⁴C]creatine uptake. *P < 0.05 (n = 3).