Oxidative stress and cardiovascular injury: Part II: animal and human studies.

Abstract

This review so far has considered the role of vascular cells in the generation of reactive oxygen species (ROS) and novel approaches to their detection in integrated systems such as animal models of vascular disease and humans. We now turn attention to evidence consistent with a role for ROS in models of human disease and in discrete patient populations. We also briefly comment on the outcomes of clinical trials of antioxidants. Mainly, these have been disappointing. However, it is premature to conclude that the oxidation hypothesis of disease causality has been adequately tested. Animal studies, for the most part, support a fundamental role for ROS in cardiovascular disease. Any controversy could in part reflect the use of ineffective antioxidants and the selection of models in which ROS generation is of marginal relevance to the measured outcome. Both of these issues require a quantitatively accurate measurement of drug effect (ie, antioxidant capacity) before hypotheses relating to the role of oxidant stress can be addressed rationally. These issues pertain to clinical trials also, as we will discuss. However, animal studies permit administration of much more powerful antioxidants (eg, rate constant for interaction of superoxide dismutase (SOD) with O2·− ≈1.6×109 · mol/L−1 · s−1) than is possible in humans (eg, rate constant for vitamin E ≈0.59 mol/L−1 · s−1) or, like in the case of vitamin E, doses of the antioxidant in excess of those usually applied in clinical research. ### Atherosclerosis Animal models of atherosclerosis have documented that all the constituents of the plaque produce and use ROS. Lesion formation is associated with the accumulation of lipid peroxidation products1,2 and induction of inflammatory genes,3 inactivation of NO·resulting in endothelial dysfunction, 4,5 activation of matrix metalloproteinases,6 and increased smooth muscle cell growth.7 …