IN-VIVO MEASUREMENT OF CHLORIDE AND WATER SECRETION IN THE JEJUNUM OFCYSTIC-FIBROSIS PATIENTS

In the present study, we have investigated the possible con sequences of the chloride channel defect in the intestine of cystic fibrosis (CF ) patients for electrolyte and water transport in the jejunum iia vivo , using a multilumen, double occluding balloon catheter, and an Ag/AgC l intraluminal electrode. During a chloride-free perfusion, to optimiz e the sensitivity of our measurements, the transmural potential differ ence (PD) (lumen with reference to serosal side) was found to be signi ficantly higher in the jejunum of CF patients (+8.0 +/- 2.1 mV; n = 5) than in healthy control subjects (-2.2 +/- 2.0 mV; n = 9). The chlori de concentration measured in chloride-free jejunal perfusates of CF pa tients was significantly lower than in controls (10.9 +/- 23 and 41.4 +/- 8.2 mM, respectively). Possible differences in net chloride and wa ter secretion did not reach statistical significance (chloride secreti on controls: 2.1 +/- 0.9 mmol/10 cm/h; CF: -0.8 +/- 0.2 mmol/10 cm/h; water secretion controls: -0.8 +/- 2.5 mL/10 cm/h; CF: -11.7 +/- 8.9 m L/10 cm/h). in control subjects, intraluminally applied theophylline s timulated the secretion of water (Delta 23.4 +/- 4.6 mL/10 cm/h) and c hloride (Delta 4.1 +/- 1.1 mmol/10 cm/h), but not in CF patients (resp ectively Delta 3.6 +/- 3.3 mL/10 cm/h and Delta 1.1 +/- 1.1 mmol/10 cm /h). In controls, the ophylline caused a significant increase in lumen negativity CPD -10.2 +/- 2.6 mV), but no change could be seen in CF p atient transmural PD. These observations provide in vivo evidence for a decreased chloride permeability in the jejunum in CF, resulting in a significant reduction in net electrolyte and water secretion in the p resence, but not in the absence, of an intestinal secretagogue.