X-ray micro-analysis of cultured respiratory epithelial cells from patients with cystic fibrosis

X-ray micro-analysis was carried out on cultured respiratory cells from polyps removed from individuals with and without cystic fibrosis (CF). In a first set of experiments, proper experimental conditions were established. Washing the cells with 300 mmol 1^-1 mannitol in distilled water was found to give the best removal of the culture medium. The elemental concentrations stabilized in about 10 min after the start of the preincubation. Intracellular Na] and Cl] increased slightly with increasing passage number, whereas intracellular K] decreased. Under resting conditions there were no significant differences in elemental content between CF and control cells, and there were no indications for abnormally high total Ca] in CF cells. In normal cells, stimulation with a cAMP-analogue resulted in a decrease of cellular CI], whereas in CF cells an increase was measured. Exposure of both normal and CF cells to ouabain resulted in decreased K] and increased Na] and CI] level. The calcium ionophore A23187 had a similar effect on normal cells but did not affect CF cells markedly. Application of amiloride to the apical side of the cells resulted in a decrease of cellular Na] in CF cells, whereas Na] in control cells was not affected. The results correspond with what is known about the defective cAMP-regulated transepithelial Cl-transport in CF cells. The effect of the calcium ionophore on cellular electrolyte content is more complicated and may be the result of two separate effects: efflux of Cl^- via a Ca²⁺-dependent mechanism and inhibition of the Na⁺-K⁺-ATPase by intracellular Ca²⁺ ions causing an influx of Na⁺ and Cl^- ions.