Effect of ruthenium red on the Ca2+ and Sr2+ efflux from rat liver mitochondria: Influence of nupercaine

The rate of ruthenium-red-induced Ca2+ efflux depends on the time that the calcium interacts with the mitochondria prior to the addition of the inhibitor. This time-dependency is abolished in the presence of nupercaine; it does not occur in the case of Sr2+ efflux from mitochondria in which the endogenous Ca2+ has been substituted by strontium (strontium-treated mitochondria, STM). Ruthenium red inhibits the respiratory-inhibitor- or uncoupler-induced Sr2+ efflux from STM, but not the Ca2+ efflux from standard mitochondria. The influence of the calcium-induced mitochondrial damage upon the effect of ruthenium red is discussed.