Vasotropic substances in blood in intestinal ischemia shock

Abstract

Serial, simultaneous rat mesoappendix assays of portal, hepatic, and femoral vein plasma in dogs in SMA shock (temporary ligation of the superior mesenteric artery) indicated the elaboration of an epinephrine inhibiting (eI) substance which appeared first in the portal vein. In dogs protected by intraportal vein injection of Dibenzyline, after onset of intestinal ischemia, an eI response was observed only in the portal vein, from which it disappeared within 8 hr. In vitro incubation of eI plasma with antiferritin serum inactivated the vasoinhibitory effects of most samples. Assay of shock plasma on the isolated rat gastric muscle strip elicited contractile responses. Pre-exposure of the muscle strip to BOL-148, a serotonin antagonist, attenuated this response. These myogenic effects were not altered by antiferritin serum or atropine. A progressive fall in plasma-bound iron levels was found in SMA portal blood. These findings establish the intestinal origin of vasotropic material in SMA shock. This material exhibits the vasotoxic properties of ferritin and the myogenic properties of serotonin.