Figure 4. Selective activation of mitoK_ATP by diazoxide in cardiomyocytes.

A, diazoxide causes reversible and reproducible oxidation of mitochondrial flavoproteins (Diazo; 100 μm). The fluorescence signal can be calibrated by maximally oxidizing (with the uncoupler 2,4-dinitrophenol; DNP) and reducing the mitochondria (with the cytochrome oxidase inhibitor cyanide; CN). B, in the same experiment, diazoxide did not activate sarcolemmal K_ATP current. Severe metabolic inhibition with DNP or CN activated sarcolemmal K_ATP, confirming the presence of these channels. From Liu et al. (1998).