Ruthenium red-induced loss of matrix K+ from uncoupled heart mitochondria

Ruthenium red induces the loss of endogenous K⁺ from isolated beef heart mitochondria treated with an uncoupler. This induction of K⁺ loss occurs at the same ruthenium red titer as the inhibition of the Ca²⁺-uniporter. This raises the possibility that ruthenium red may alter the Ca²⁺-uniporter in such a way as to produce a K⁺-conducting channel.