Figure 2. Blockers of the putative mitochondrial ATP-sensitive K⁺ channel (mitoK_ATP) did not affect an initial decrease in light absorbance of suspension of isolated brain mitochondria (A) or mitochondrial matrix volume measured with radioisotopes (B).

Mitochondria were incubated in the KCl-based incubation medium supplemented with 3 mm succinate and 3 mm glutamate. A, representative traces obtained with 0.5 mm ATP, 0.5 mm 5-hydroxydecanoate (5-HD) and 4 μm tetraphenylphosphonium cation (TPP⁺), and without (control). The blockers were added to the medium prior to adding mitochondria (Mtc). B, summary of the radioisotope measurements of the mitochondrial matrix volume. Matrix volume at time zero was measured on ice as outlined in Methods. In other experiments, mitochondria were incubated for 5 min with or without the blockers of the putative mitoK_ATP at 37°C prior to determination of the matrix volume. Data are means ±s.e.m., n = 5.