Abstract

The benzimidazole derivative NS1619 is a known activator of large-conductance calcium-activated potassium (BKCa) channels, but its effects on mitochondrial bioenergetics remain less characterized. This study aimed to investigate the direct impact of NS1619 on the functioning of mitochondria isolated from mouse skeletal muscle, a tissue with high metabolic demand. Using high-resolution respirometry and fluorescent probes, we assessed key parameters of mitochondrial function, including oxygen consumption rates, respiratory control ratio, and membrane potential. Our findings demonstrate that NS1619 significantly inhibits mitochondrial respiration in a concentration-dependent manner, primarily by acting as an uncoupler and partially inhibiting Complex I of the electron transport chain. Specifically, NS1619 reduced the respiratory control ratio and induced a dose-dependent decrease in mitochondrial membrane potential, suggesting a disruption of the proton gradient necessary for ATP synthesis. These results highlight a novel, off-target effect of NS1619 on the inner mitochondrial membrane, suggesting that its therapeutic use may be complicated by direct interference with cellular energy metabolism. This work contributes to a better understanding of the pharmacological profile of benzimidazole derivatives and their potential as modulators of mitochondrial function in skeletal muscle physiology and disease.