HUMAN PROXIMAL DUODENAL ION AND WATER TRANSPORT - ROLE OF ENTERIC NERVOUS-SYSTEM AND CARBONIC-ANHYDRASE

Intestinal ion transport is mediated by the interaction of enterocyte function, the enteric nervous system, humoral agents, and mucosal prod uction of carbonic anhydrase. Our purpose was to examine the effect of the carbonic anhydrase inhibitor acetazolamide and inhibition of the enteric nervous system with the topical anesthetic lidocaine on basal and prostaglandin E(2)-stimulated ion and water transport and transmuc osal electrical potential difference. At rest, mean basal (95% confide nce intervals) net ion secretion into the human proximal duodenum was: Cl- 670 (288-1052), Na+ 818 (410-1225), K+ 32 (14-51) mu mol/cm/hr. B asal net water transport was 30 (14.6-45.3) ml/hr, and the potential d ifference (PD) was 7.0 (3.6-10.9) mV, lumen negative. Intraluminal pro staglandin E(2) increased the secretion of all ions, water, and the PD . After pretreatment with acetazolamide and luminal administration of lidocaine, basal ion transport was unchanged, but the response to lumi nal PGE(2) was inhibited. It is concluded that: (1) at rest there is a net secretion of Na+, K+, Cl-, and water by the human proximal duoden um; and (2) PGE(2)-stimulated water electrolyte secretion is dependent in part upon mucosal carbonic anhydrase activity and the enteric nerv ous system.