EFFECTS OF MESENTERIC ISCHEMIA AND REPERFUSION ON SMALL-BOWEL ELECTRICAL-ACTIVITY

Previous studies involving basic electrical rhythm (BER) have not been carried out far enough to fully characterize the relationship between mesenteric ischemia and BER. The phenomenon of reperfusion injury has also not been correlated with BER activity. The goal of this study wa s to characterize changes in BER during mesenteric ischemia and reperf usion and to correlate them with changes in pathology. Methods. Serosa l electrodes were used to record the electrical activity of rabbit jej unum (n = 20) at baseline, during ischemia (90-210 min), and during re perfusion (120-240 min). BER frequency and amplitude were monitored, a nd biopsies were taken at the end of ischemia and reperfusion. A patho logist blinded to the specimen identity graded the histology on a scal e of 0 (no changes) to 6 (transmural necrosis). Paired t test, the Kru skal-Wallis test of nonparametric ranks, and Fisher's r to z test were used for statistical significance where appropriate. Results. BER fre quency and amplitude fell significantly after 15 min of ischemia and b ecame undetectable by 90 min of ischemia in all animals. The likelihoo d that BER would return during reperfusion was highly correlated with length of ischemia (r = 0.99). Longer periods of reperfusion were asso ciated with increasing pathologic grade. Conclusions. BER frequency an d amplitude are very sensitive to ischemia and their changes occur wel l before histopathologic changes. The variation in electrical activity of the small bowel during ischemia and reperfusion is a dynamic proce ss that reflects the metabolic state of the smooth muscle, if electric al activity of the bowel is to be used for assessment of viability, co ntinuous recordings more accurately reflect the metabolic state of the smooth muscle. (C) 1998 Academic Press.