Small-Bowel Transplantation in the Rat: Graft Survival with Heterotopic vs Orthotopic Position

Abstract

Experimental studies on a variety of vascularized organ allografts have suggested that graft rejection may be delayed if venous outflow is directed into the portal rather than the systemic circulation (Fukuda et al. 1969; Sakai 1970). In studies of small-bowel transplantation, in which portal rather than caval venous drainage establishes an anatomically and physiologically normal state, the beneficial effects of portal drainage on the survival of both graft and recipient have been confirmed (Kort et al. 1973; Schraut et al. 1983). These studies, however, have been limited to the heterotopic model of intestinal transplantation in which the small-bowel allograft remains defunctionalized, i.e., it constitutes an accessory graft which is not in continuity with the recipient’s gastrointestinal tract. In future clinical intestinal transplantation, the graft is likely to be placed orthotopically, in gastrointestinal continuity, either at the time of transplantation or later. In this position, the intestinal allograft is exposed to the fecal stream and is required to absorb enterally administered nutrients. Using the rat model of vascularized small-bowel transplantation, we studied the effect of venous drainage upon graft survival following both heterotopic and orthotopic transplantation.