Reactive oxygen species (ROS) are now appreciated to play several important roles in a number of
biological processes and regulate cell physiology and function. ROS are a heterogeneous chemical class that
includes radicals, such as superoxide ion (O2•-), hydroxyl radical (OH•) and nitric oxide (NO•), and non-radicals,
such as hydrogen peroxide (H2O2), singlet oxygen (1O2), hypochlorous acid (HOCl), and peroxynitrite (NO3
the cardiovascular system, besides playing a critical role in the development and progression of vasculopathies
and other important pathologies such as congestive heart failure, atherosclerosis and thrombosis, ROS also
regulate physiological processes. Evidence from a wealth of cardiovascular research studies suggests that
ROS act as second messengers and play an essential role in vascular homeostasis by influencing discrete
signal transduction pathways in various systems and cell types. They are produced throughout the vascular
system, regulate differentiation and contractility of vascular smooth muscle cells, control vascular endothelial
cell proliferation and migration, mediate platelet activation and haemostasis, and significantly contribute to the
immune response. Our understanding of ROS chemistry and cell biology has evolved to the point of realizing
that different ROS have distinct and important roles in cardiovascular physiology. This review will outline
sources, functions and molecular mechanisms of action of different ROS in the cardiovascular system and will
describe their emerging role in healthy cardiovascular physiology and homeostasis.
Cardiovascular system, endothelial, hydrogen peroxide, platelet, reactive oxygen species, redox,
smooth muscle, superoxide anion.
Department of Pharmacy and Pharmacology, Centre for Regenerative Medicine, Claverton Campus, University of Bath, Bath, BA2 7AY, UK.