Cardiac output distribution before and after endotoxin challenge in the rooster.

Cardiac output and its distribution to selected organs was studied using radiolabeled microspheres in unanesthetized, restrained white Leghorn roosters before and 3 h after an Escherichia coli endotoxin challenge. Cardiac output was not significantly altered in either control or endotoxin-treated animals, nor was there a difference in cardiac output between the two groups. Systemic arterial pressure decreased by 37% in the endotoxin group from 187 +/- 14 to 117 +/- 9 mmHg, thus reflecting a marked reduction in total peripheral resistance. The fraction of cardiac output perfusing the heart, adrenals, and liver (hepatic arterial) was not altered by the challenge. Conversely, the percent of total blood flow received by the kidneys, pancreas, and gut (proventriculus and duodenum) was significantly (P less than 0.05) reduced during endotoxemia. Absolute flow to the brain was also decreased. These findings demonstrate that in the rooster endotoxin-induced systemic arterial hypotension is a sufficient stress to cause a redistribution of blood flow, and that the brain in this species (unlike its counterpart in mammals) probably regulates its blood supply passively during periods of hypotension. Conversely, the reduced blood supply to such organs as the gut, pancreas, and kidney following the endotoxin challenge is similar to changes seen in the more commonly studied mammals during experimental endotoxemia.