Superoxide Dismutase in Bovine Fetal Ductus Arteriosus, Thoracic Aorta, and Pulmonary and Umbilical Arteries

Abstract

Soon after birth the lumens of the ductus arteriosus (DA) and umbilical artery (UA) are obliterated [in fetal calves]. O2 toxicity, resulting from an increased O2 tension, is the cause of this destruction with superoxide radicals and hydroxyl radicals being implicated as mediators. A deficiency of superoxide dismutase (SOD) in these tissues was hypothesized as being responsible for an increase in the levels of superoxide and hydroxyl radicals. SOD levels were determined enzymatically and immunochemically in 4 tissues obtained from 13 bovine fetuses. SOD levels in the DA and UA were found by both assays to be statistically lower than that found in such permanent vessels as the pulmonary artery and thoracic aorta. A lower level of SOD in the ductus arteriosus and umbilical artery may contribute to the rapid deterioration of these tissues upon exposure to greatly increased O2 tensions.