The work which comprises this thesis concerns the effects of oxygen-derived free radicals and reactive oxygen species on the intracellular organelles of force production and calcium storage in cardiac muscle. In addition, the possibility of endogenous histidine-containing compounds having antioxidant activity has been investigated. Preparations treated with Triton-X100 retain only traces of membrane structure while the contractile proteins remain functional. This form of treatment is ideal for investigating alterations to myofilament calcium sensitivity and maximum calcium-activated force production. Saponin-treated trabeculae retain the intracellular membranes associated with the sarcoplasmic reticulum and the mitochondria, while the sarcolemma is rendered permeable to the experimental solutions. This form of treatment is ideal for investigating alterations to sarcoplasmic reticulum and mitochondrial function
