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

Abstract

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 l-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 [Cl], 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 [Cl] 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 Ca(2+)-dependent mechanism and inhibition of the Na(+)-K(+)-ATPase by intracellular Ca2+ ions causing an influx of Na+ and Cl- ions.