AUTHOR=Lindsay Daniel P. , Camara Amadou K. S. , Stowe David F. , Lubbe Ryan , Aldakkak Mohammed TITLE=Differential effects of buffer pH on Ca2+-induced ROS emission with inhibited mitochondrial complexes I and III JOURNAL=Frontiers in Physiology VOLUME=6 YEAR=2015 URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2015.00058 DOI=10.3389/fphys.2015.00058 ISSN=1664-042X ABSTRACT=
Excessive mitochondrial reactive oxygen species (ROS) emission is a critical component in the etiology of ischemic injury. Complex I and complex III of the electron transport chain are considered the primary sources of ROS emission during cardiac ischemia and reperfusion (IR) injury. Several factors modulate ischemic ROS emission, such as an increase in extra-matrix Ca2+, a decrease in extra-matrix pH, and a change in substrate utilization. Here we examined the combined effects of these factors on ROS emission from respiratory complexes I and III under conditions of simulated IR injury. Guinea pig heart mitochondria were suspended in experimental buffer at a given pH and incubated with or without CaCl2. Mitochondria were then treated with either pyruvate, a complex I substrate, followed by rotenone, a complex I inhibitor, or succinate, a complex II substrate, followed by antimycin A, a complex III inhibitor. H2O2 release rate and matrix volume were compared with and without adding CaCl2 and at pH 7.15, 6.9, or 6.5 with pyruvate + rotenone or succinate + antimycin A to simulate conditions that may occur during