Presence of a reticuloendothelial depressing substance in portal vein blood following intestinal ischemia and thermal injury.

This study was carried out to determine if an RE depressing substance is present following intestinal ischemia or thermal injury. Intestinal ischemia consisted of occluding the celiac and mesenteric arteries for 3 hr, and thermal injury was a 30% body-surface-area scald (30 sec in 90 degrees C water) in dogs anesthetized with sodium pentobarbital. Immediately following release of the arterial occlusions or 3 hr after thermal injury, portal vein blood was collected and plasma extracts prepared. RE depressing substance activity was assayed by measuring the colloidal carbon clearance rate in rats following the IV injection of the plasma extracts or saline. Plasma extracts from control animals never had detectable RE depressing substance activity. Following intestinal ischemia RE depressing activity was consistently detected in 6 assays on plasma extracts from 12 animals. Thermal injury was associated with the presence of RE depressing activity in each of the 4 animals studied. Neither intestinal ischemia or thermal injury was associated with a significant decrease in mean arterial blood pressure. These results indicate that RE depressing substance may contribute to the RES depression and impaired host-defense seen following intestinal ischemia and thermal injury.