Burn edema and protein leakage in the rat. I. Relationship to time of injury.

Abstract Studies to determine the relationship between increased vascular permeability (water content and protein leakage) and time postinjury were performed in rats. Three small, thermal burns were inflicted to the left of the spine. Animals were sacrificed at the following time intervals postinjury: 0.5, 1.5, 3, 6, 12, 18, 24, 36, and 48 hr. Radio-iodinated human serum albumin (131I-RISA), 200 μCi/kg body weight, was given iv 30 min prior to sacrifice. Segments of skin were obtained, weighed, counted (scintillation counting), dried (60° for 96 hr), and reweighed. Autoradiographic studies were also performed. Water content was maximal at 3 h postburn and was no longer demonstrable by 24 hr. Albumin leakage was maximal at 30 min and disappeared by 12 hr postinjury. In another set of experiments in which 131I-RISA was injected at the time of the burn, high tissue counts persisted for as long as 48 hr. These studies have shown that abnormal albumin extravasation occurs only during the first 6 to 12 hr postinjury. Once in the interstitium, however, albumin may remain trapped for up to 48 hr.