Meal-induced jejunal absorption requires intact neural pathways

A signal for meal-induced absorption originates from the small intestine and is transmitted to a luminally excluded segment of the proximal jejunum (Thiry-Vella [TV] fistula). Using intraluminal topical anesthesia with oxethazaine, this study assessed the role of intestinal neural pathways in basal and postprandial jejunal water and electrolyte absorption. Studies (n = 45) were performed on dogs with 25-cm proximal jejunal TV fistulae and feeding jejunostomies, using luminal perfusion with ¹⁴C-polyethylene glycol. The animals were randomized into five study groups: (1) jejunostomy oxethazaine alone, (2) jejunostomy water and jejunal meal, (3) jejunostomy oxethazaine and jejunal meal, (4) TV fistula water and jejunal meal, and (5) TV fistula oxethazaine and jejunal meal. The jejunal meal significantly increased TV fistula absorption, whereas oxethazaine significantly reduced basal absorption when administered via the TV fistula and postprandial absorption when administered via the jejunostomy (p < 0.05). TV fistula oxethazaine did not diminish the magnitude of postprandial absorption. We conclude that intact intestinal neurotransmission is necessary for maintenance of the normal basal absorptive state of the proximal jejunum and for the generation of a normal meal-stimulated proabsorptive signal from the small intestine. A nonneural mechanism appears to be of predominant importance in transmitting the proabsorptive signal from the intact gastrointestinal tract to the TV fistula.