Jejunal responses to absorptive and secretory stimuli in the neurally isolated jejunum in vivo.

BACKGROUND: Our aim was to assess changes in transport of water and electrolytes under basal, proabsorptive, and prosecretory conditions after an in situ neural isolation of the jejunoileum.
METHODS: Eight dogs underwent intraoperative perfusion of 50 cm of jejunum with a balanced electrolyte solution during sham operation and after neural isolation of the jejunoileum. Jejunal perfusion studies were later conducted in seven conscious dogs with a triple-lumen technique before and 2 and 8 weeks after neural isolation of the jejunoileum during intravenous infusion of 150 mmol/L sodium chloride (basal conditions), vasoactive intestinal polypeptide (VIP conditions), 500 pmol/kg per hour (prosecretory conditions), and the alpha 2-adrenergic agonist alpha-methylnorepinephrine (MNE), 900 nmol/kg per hour (proabsorptive conditions).
RESULTS: Neural isolation decreased intraoperative net absorption of water (4.4 +/- 0.9 vs 2.2 +/- 0.5 microliters/cm/min; p < 0.05) and electrolytes (sodium, chloride, bicarbonate, potassium). In conscious dogs during basal conditions, net absorptive flux was decreased (p < 0.05) at 2 but not at 8 weeks. VIP produced similar absolute decreases in net absorptive flux at all three time points. MNE increased net absorption before and at 8 weeks, but not at 2 weeks after autotransplantation.
CONCLUSIONS: In situ neural isolation of the jejunoileum decreased net basal jejunal absorption of water and electrolytes immediately and for at least 2 weeks. Proabsorptive responses to MNE but not prosecretory responses to VIP were altered at 2 weeks. Jejunal adaptation allowed absorptive function to return to near normal by 8 weeks.