Superoxide anion selectively attenuates catecholamine-induced contractile tension in isolated rabbit aorta

anion selectively attenuates catecholamine-induced contractile tension in isolated rabbit aorta. Am. J. Physiol. 249 (Heart Circ. Physiol. 18): H1127-H1133, 1985.-Xanthine oxidase-derived oxygen metabolites caused a selective loss of norepinephrine-induced contractile tension in rings and helical strips from rabbit aorta. Phenylephrine-induced tension was not affected. The relaxation was selectively and completely blocked by su-peroxide dismutase but not by catalase. Isoproterenol-induced relaxation was also reversed by xanthine oxidase-derived oxy-gen metabolites. These observations are consistent with the chemical reaction of superoxide anion with catecholamines and suggest hat the reaction may have significance at physiological concentrations of norepinephrine. The time course of the ef-fects of superoxide generation on contractile tension was con-sistent with the properties of the chemical reaction (measure