ION-TRANSPORT ACROSS THE MURINE INTESTINE IN THE ABSENCE AND PRESENCEOF CFTR

CF mice, i.e., mice without functional CFTR (cystic fibrosis transmemb rane conductance regulator) exhibit a very low basal I-sc in all regio ns of the intestinal tract. The low basal I-sc in the intestinal epith elia of the CF mice appears to be a result of lack of spontaneous Cl- secretion (and possibly HCO3- secretion) mediated by neurotransmitter release from the enteric nervous system.In contrast to intestinal epit helia from normal mice, the intestinal epithelia of CF mice do not sec rete Cl- in response to agents that increase cAMP (forskolin). Further more, as in human CF patients, agents that increase intracellular Ca2 (bethanacol, ionomycin) failed to elicit Cl- secretion in the intesti nal epithelia of CF mice. There was no difference in the electrogenic Na+-coupled glucose absorption in the CF murine jejuna compared to jej una from normal mice. However, further studies are warranted to determ ine whether amiloride-sensitive Na+ absorption is upregulated in the m urine CF colon. It was concluded that the intestinal epithelium of the CF mouse model exhibits some striking similarities to its human count erpart, and therefore should be very useful in further characterizing the ion transport defects in this disease. (C) 1997 Elsevier Science I nc.