Effects of hydrogen peroxide on pig coronary artery endothelium

Peroxides and other reactive oxygen species damage arteries during ischemia -reperfusion. Here, we report on the effects of H2O2 on contractility of pi g coronary artery. We either treated 3-mm coronary artery rings with 0 to 0 .5 mM H2O2 in organ baths or we perfused the arteries with H2O2 and then cu t them into rings. In each instance, we monitored the force of contraction of 3-mm rings in H2O2-free solution with 30 mM KCI and then we determined t he A23187 induced endothelium dependent relaxation as a percent of this con traction. Treatment with H2O2 in the organ bath caused a decrease in the co ntraction but it did not affect the percent relaxation. Treating arteries w ith H2O2 by luminal perfusion did not affect the contraction but it decreas ed the percent relaxation. Perfusion alone decreased the amount of endothel ium remaining in the arteries and perfusing with H2O2 decreased it further. The percent relaxation with A23187 correlated well with the endothelium re maining in the arteries. We propose that H2O2 and shear stress can cause a loss of endothelium and that endothelium can also protect the underlying sm ooth muscle against luminal H2O2. (C) 2000 Published by Elsevier Science B. V.