Abstract
Summary
Soon after birth the lumens of the ductus arteriosus (DA) and umbilical artery (UA) are obliterated. It has been suggested that oxygen toxicity, resulting from an increased oxygen 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 four tissues obtained from thirteen bovine fetuses. SOD levels in the DA and UA were found by both assays to be statistically significantly lower than that found in such permanent vessels as the pulmonary artery and thoracic aorta. These data are in support of the hypothesis that 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 oxygen tensions.
The kind assistance of Iowa Beef Processors of Dakota City, Nebraska in obtaining calf fetuses is acknowledged. The technical assistance of two fellow medical students, Curt Bucholz and Ron Thune, and of an undergraduate student, Mark Martin, is appreciated. Supported by General Research Support Grant from the National Institutes of Health (USPHS 01 RR 05421-14). Frank O. Brady is a Research Career Development Awardee of the National Institute of Environmental Health Sciences, NIH (ES 00022).
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