ENDOTOXIN INDUCES BIPHASIC ALTERATIONS IN SMALL-INTESTINAL MYOELECTRIC ACTIVITY IN FASTED NEWBORN PIGLETS

Previous studies have shown that i.v. endotoxin infusion causes gastro intestinal dysfunction and intestinal injury in piglets. The aim of th is study was to investigate the effects of endotoxin on intestinal myo electric activity in newborn swine and to correlate this with gastroin testinal and hemodynamic events. Three pairs of electrodes were implan ted in the jejunal wall of piglets, and after recovery, intestinal myo electric activity was continuously recorded in the conscious, fasted c ondition. The intestinal myoelectric activity on the control day showe d regular, repeating migrating myoelectric complex (MMC) cycles, each of which was composed of the classic phases I, II, and III. Mean cycle duration was 67.0 +/- 18.7 min (+/-SD), and phase III comprised 9.1 /- 2.2% of each cycle. On the next day, infusion of 30 mu g/kg endotox in caused an initial, prolonged quiescent period and delayed the appea rance of the first postendotoxin phase III complex. After the quiescen t period, there was a period of irregular spiking activity followed by several shortened MMC cycles (47.9 +/- 22.7 min, p < 0.01 versus cont rol) with a prolongation of the percentage of time spent in phase III (15.4 +/- 11.3%, p < 0.01). Endotoxin thus produced biphasic alteratio ns in intestinal myoelectric activity characterized by an initial quie scence followed by increased gastrointestinal smooth muscle activity. Animals developed diarrhea, hypotension, and tachycardia about 1 h aft er endotoxin infusion in temporal association with increased spiking a ctivity and MMC cycling. These studies are the first to show this biph asic response to endotoxin.