Blood flow clearance changes in pig skin after single doses of X rays

Early and late changes in the functional vascularity of pig skin have been evaluated after X-irradiation. These changes were assessed using a quantitative isotopic clearance technique. Two waves of radiation-induced changes in isotopic clearance were demonstrated. The first wave, observed after an interval of three weeks, was characterized by the faster clearance of the tracer from areas of irradiated skin. The second wave, which reached a peak after 12 weeks, was denoted by a slowing of the clearance rate relative to normal skin. The modification in vascular function observed at 12 weeks was transient, function returning to normal as late radiation damage developed. The changes observed in the pig have many similarities with those recorded in man but are markedly different from those found in rodents. These differences are discussed with respect to the vascular structure of the skin of the animal species investigated.