Figure 2. Effects of AA5 on mK_ATP channel activity in isolated rat heart mitochondria.

mK_ATP activity was determined by osmotic swelling assay as described in the methods. (A): Representative swelling traces of mitochondria (~0.25 mg/ml) in K⁺ media supplied with succinate (2 mM) as respiratory substrate. Optical density (OD) at 520 nm is on the y-axis. Where indicated, 1 mM ATP (black squares), 1 nM AA5 plus ATP (gray squares), or 300 μM 5HD plus AA5 plus ATP (open triangles) were present in the media. (B): Magnitude of swelling relative to controls, determined by the decrease in OD after 0.2 min. in either K⁺ media (black bars) or Na⁺ media (gray bars). Delta OD₅₂₀ in controls was 0.020 ± 0.003 in K⁺ media and 0.015 ± 0.003 in Na⁺ media. Experimental conditions are listed below the x-axis. Data are means ± SEM, N>6. *p<0.05 vs. ATP alone, #p<0.05 vs. ATP + AA5.