JEJUNAL RESPONSES TO ABSORPTIVE AND SECRETORY STIMULI IN THE NEURALLYISOLATED JEJUNUM IN-VIVO

Background. Our aim was to assess changes in transport of water and el ectrolytes under basal, proabsorptive, and prosecretory conditions aft er an in situ neural isolation of the jejunoileum. Methods. Eight dogs underwent intraoperative perfusion of 50 cm of jejunum with a balance d electrolyte solution during sham operation and after neural isolatio n of the jejunoileum. Jejunal perfusion studies were later conducted i n seven conscious dogs with a triple-lumen technique before and 2 and 8 weeks after neural isolation of the jejunoileum during intravenous i nfusion of 150 mmol/L sodium chloride (basal conditions), vasoactive i ntestinal polypeptide (VIP conditions), 500 pmol/kg per hour (prosecre tory conditions), and the alpha(2)-adrenergic agonist alpha-methylnore pinephrine (MNE), 900 nmol/kg per hour (proabsorptive conditions). Res ults. Neural isolation decreased intraoperative net absorption of wate r (4.4 +/- 0.9 vs 2.2 +/- 0.5 mu l/cm/min; p < 0.05) and electrolytes (sodium, chloride, bicarbonate, potassium). In conscious dogs during b asal conditions, net absorptive flux was decreased (p < 0.05) at 2 but not at 8 weeks. VIP produced similar absolute decreases in net absorp tive flux at all three time points. MNE increased net absorption befor e and at 8 weeks, but not at 2 weeks after autotransplantation. Conclu sions. In situ neural isolation of the jejunoileum decreased net basal jejunal absorption of water and electrolytes immediately and for at l east 2 weeks. Proabsorptive responses to MNE but not prosecretory resp onses to VIP were altered at 2 weeks. Jejunal adaptation allowed absor ptive function to return to near normal by 8 weeks.