EFFECT OF REJECTION ON ELECTROPHYSIOLOGIC FUNCTION OF CANINE INTESTINAL GRAFTS - CORRELATION WITH HISTOPATHOLOGY AND NA-K-ATPASE ACTIVITY

To investigate whether electrophysiologic changes can detect the early onset and progress of intestinal rejection, changes in in vitro elect rophysiologic function, intestinal histopathology, and Na-K-ATPase act ivity were studied in dogs. Adult mongrel dogs of both both sexes, wei ghing 18-24 kg, were used for auto and allo small bowel transplantatio n. The entire small bowels, except for short segments at the proximal and distal ends, were switched between a pair of dogs (allograft). Ani mals receiving intestinal autotransplantation were used as controls. A llograft recipients were sacrificed 3, 4, 5, 7, or 9 days after transp lantation, and autograft recipients were sacrificed 3, 7, or 14 days a fter transplantation. Immunosuppression was not used. Electrophysiolog ic measurements were done with an Ussing chamber. Histological analysi s was performed blindly using whole thickness sections. Na-K-ATPase ac tivity in the mucosal tissue, which is said to regulate the potential difference, was also measured. Potential difference, resistance, and N a-K-ATPase activity of the allograft intestine decreased with time and were significantly lower 7 and 9 days after transplantation compared to host intestine, normal intestine, and graft intestine of controls ( autograft). Potential difference, resistance, and Na-K-ATPase activity of the native intestinal tissue and the autografts did not decrease w ith time. Detection of histologically mild rejection of the intestine, which is important for appropriate immunosuppressive treatment in cli nical cases, could not be achieved based on electrophysiology or Na-K- ATPase activity. Deterioration of electrophysiologic function during r ejection correlated with the histological rejection process and Na-K-A TPase activity; however, electrophysiology may not be a reliable tool for monitoring grafts, since it cannot detect early intestinal rejecti on.