Increased bronchial chloride concentration in cystic fibrosis.

Ten patients with cystic fibrosis (CF) and 10 patients with severe chronic bronchitis were analysed for bronchial electrolyte composition. Samples aspirated from the left main bronchus by a fibre-optic bronchoscope were dissolved in an iso-osmolar solution of N-acetylcysteine, and separated from cells and bacteria by gentle centrifugation. The concentrations of potassium and calcium were measured by flame emission and atomic absorption spectrometry, and found to be similar in both groups of patients. The mean concentration of chloride, measured by coulometric titration, was significantly higher in patients with CF than in patients with chronic bronchitis (170 vs. 85 mmol l-1, p less than 0.01). The findings are consistent with a functional abnormality of the chloride channels of the airway epithelium in patients with CF.