In addition to influencing signaling pathways associated with cell growth and inflammation, ROS modulate intracellular Ca2+ concentration ([Ca2+].), a major determinant of vascular contraction. Superoxide and H2O2 increase [Ca2+]i in VSMCs and endothelial cells.109 These effects have been attributed to redox-dependent inositol-trisphosphate-induced Ca2+ mobilization, increased Ca2+ influx, and decreased activation of Ca2+-ATPase.109110 Plasma membrane K+ channels in VSMCs that control a hyperpolarization-elicited relaxation are opened by mechanisms associated with thiol oxidation by ROS.99 100 110 These redox-regulated Ca2+ processes may be more important in stress responses than in receptor-mediated signaling by growth factors or cytokines and may play a role in altered vascular contractility in hypertension. In fact contractile responses to H2O2 are exaggerated in arteries from SHR compared with normotensive counterparts,111 suggesting that in addition to impaired endothelium-dependent vasodilation (due to increased quenching of NO by *O2-), redox-sensitive Ca2+ changes could contribute to altered vascular tone in hypertension.
Was this article helpful?
Do You Suffer From High Blood Pressure? Do You Feel Like This Silent Killer Might Be Stalking You? Have you been diagnosed or pre-hypertension and hypertension? Then JOIN THE CROWD Nearly 1 in 3 adults in the United States suffer from High Blood Pressure and only 1 in 3 adults are actually aware that they have it.