Exp Biol Med (Maywood). 2007 Jan;232(1):27-37.
A comparison of arteries and veins in oxidative stress: producers, destroyers,
function, and disease.
Szasz T, Thakali K, Fink GD, Watts SW.
Department of Pharmacology and Toxicology, Michigan State University, B445 Life
Sciences, East Lansing, MI 48825. email@example.com.
Reactive oxygen species (ROS) are by-products of oxygen metabolism, normally
present in low levels inside cells, where they participate in signaling
processes. The delicate balance in the continuous cycle of ROS generation and
inactivation is maintained by enzymatic and nonenzymatic endogenous systems.
Overwhelming production of ROS (by such sources as the mitochondrial electron
transport chain, NADPH oxidase, xanthine oxidase, or uncoupled nitric oxide
synthase), when inadequately counteracted by destruction through antioxidant
systems (such as superoxide dismutase or catalase), leads to a prooxidant state
also known as oxidative stress. Increased levels of ROS and markers of oxidative
stress have been consistently found in such cardiovascular diseases as
atherosclerosis or hypertension, although controversy still exists over the
pathophysiological role of oxidative stress in these conditions. ROS can
modulate vascular function either by direct oxidative damage or by activating
cellular signaling pathways that lead to abnormal contractile, inflammatory,
proliferative, or remodeling properties of the blood vessel. Most current
research focuses on these processes in arteries, leaving veins, "the other side"
of vascular biology, in obscurity. Veins are different structurally and
functionally from arteries. Equipped with a smaller smooth muscle layer compared
to arteries, but being able to accommodate 70% of the circulating blood volume,
veins can modulate cardiovascular homeostasis and contribute significantly to
hypertension pathogenesis. Although the reports on the quantitative differences
in ROS production in veins compared to arteries had conflicting results, there
is a clear qualitative difference in ROS metabolism and utilization between the
two vessel types. This review will compare and contrast the current knowledge of
ROS metabolism in arteries versus veins in both physiological and
pathophysiological conditions. Our understanding of the mechanisms underlying
vascular diseases would greatly benefit from a more thorough exploration of the
role of veins and venous oxidative stress.