Gastrointestinal blood flow in the opossum with special reference to the esophagus

Abstract

The opossum esophagus, like that of the human, is composed of striated muscle fibres proximally and smooth muscle fibres distally. Because of this similarity the opossum has been used extensively as an animal model for esophageal studies, but to date no data on esophageal blood flow have been reported in this species. The purpose of this study was to establish the basal blood flow characteristics of different regions of the opossum gastrointestinal tract with particular reference to the esophagus. Intracardiac injection of 15-microns microspheres was used to provide an estimate of blood flow (mL.min-1.g-1 dry tissue) to the whole wall, the combined layer of mucosa plus submucosa, and the muscularis propria. Basal blood flow in the whole tissue and mucosa-submucosa was significantly higher in the lower esophageal sphincter than in the proximal or distal esophagus. The muscularis propria blood flow displayed an aborally increasing gradient with flow to proximal esophagus (striated muscle) less than distal esophagus (smooth muscle) less than lower esophageal sphincter. Regional differences in blood flow to other regions of the gastrointestinal tract were similar to that described in other species. In addition, no changes in basal blood flow occurred despite repeated microsphere injections, suggesting that this species provides a good animal model for the study of gastrointestinal blood flow.

Effect of esophageal contraction on esophageal wall blood perfusion

“…Esophageal blood flow has been studied using various techniques, in animals and humans. Using microsphere injection technique, it was determined that the blood flow to the opossum lower esophageal sphincter is greater than that to the body of the esophagus (19). Mucosa and submucosa receive greater blood flow than the muscular proporia, and there is a gradient of blood flow in the esophagus; the distal part receives greater blood flow than the proximal.…”

Anastomotic and Regional Blood Flow Following Esophagogastrectomy in an Opossum Model

“…We measured blood ow at the esophagog astric anastomosis and at the esophageal and gastric pedicles following an esophagog astrectomy in the opossum, an accepted model of esophageal physiology with vascular anatomy similar to the human [15][16][17]. We hypothesized that devascularization of the stomach and the esophagus would reduce blood ow to these organs and that this impaired blood ow would be improved by increasing endogenous nitric oxide.…”