Partial analysis of segmental resistances in intestinal vessels after endotoxin

Abstract

Hemodynamic responses of intestinal vascular segments of the dog to intravenous administration of a lethal dose (1 mg/kg) of E. coli endotoxin were investigated. Pressures were measured in large and small vessels of the intestinal and mesentery (small veins 30–60 µ in radius). Vascular radii of submucosal vessels and blood flow were determined. Changes in total resistance in the intestinal circulation after endotoxin were not uniform during the first few minutes, but there was a significant decrease at 10 min and a subsequent rise to the control value after 1 hr. At both 50 and 60 min, the resistance was increased over control in the arterial segment by 50%, increased 500% in the venous segment, and decreased 40% in the segment from small artery to venule. These circumstances would increase capillary pressure and filtration of edema fluid. Increased wall tension at reduced diameter developed in the venous segment during the secondary shock state, whereas relaxation of wall tension occurred in the arteriolar segment.