Functional evidence of Hv1-mediated proton flux in cardiac mitochondria

Mitochondria are essential for cardiac myocyte function, providing the continuous ATP supply required for contraction and cellular homeostasis. Regulation of the proton motive force, which is critical for ATP synthesis, depends on multiple ion transport mechanisms, including those mediating H⁺ flux. The voltage-gated proton channel (Hv1), encoded by the Hvcn1 gene, is known to regulate cytosolic pH and membrane potential in several cell types. Here, using isolated mouse cardiac mitochondria, we demonstrate for the first time that Hv1 is functionally expressed in cardiac mitochondria. Pharmacological inhibition of Hv1 enhanced matrix alkalinization and induced mitochondrial hyperpolarization during succinate-driven mitochondrial energization. Importantly, a similar hyperpolarization was also observed under basal conditions in intact cardiac myocytes.