Fig. 2.

Stimulation of AMPK results in increased membrane association of AQP2. A: representative Western blot of AQP2 in the biotinylated protein fraction from rat inner medulla treated for 30 min with 400 μM metformin. The bar graph shows the average band density from n = 8 animals per condition from 2 experiments. Bar = means ± SE, *P < 0.05. B: immunohistochemistry of AQP2 in kidneys of rats treated with metformin for 30 min before paraformaldehyde fixation of the kidneys as described in methods. Left: untreated control rat kidney; right: metformin-treated rat kidney (×400 magnification). C: osmotic water permeability measured by perfusion of isolated inner medullary collecting ducts (IMCDs) in response to stimulation of AMPK with 400 μM metformin. Each line represents a separate tubule from a separate animal. Bars, means ± SE, n = 4, #P < 0.05.