Composition of nasal airway surface liquid in cystic fibrosis and other airway diseases determined by X-ray microanalysis.

The ionic composition of the airway surface liquid (ASL) in healthy individuals and in patients with cystic fibrosis (CF) has been debated. Ion transport properties of the upper airway epithelium are similar to those of the lower airways and it is easier to collect nasal ASL from the nose. ASL was collected with ion exchange beads, and the elemental composition of nasal fluid was determined by X-ray microanalysis in healthy subjects, CF patients, CF heterozygotes, patients with rhinitis, and with primary ciliary dyskinesia (PCD). In healthy subjects, the ionic concentrations were approximately isotonic. In CF patients, CF heterozygotes, rhinitis, and PCD patients, [Na] and [Cl] were significantly higher compared when compared with those in controls. [K] was significantly higher in CF and PCD patients compared with that in controls. Severely affected CF patients had higher ionic concentrations in their nasal ASL than in patients with mild or moderate symptoms. Female CF patients had higher levels of Na, Cl, and K than male patients. As higher salt concentrations in the ASL are also found in other patients with airway diseases involving chronic inflammation, it appears likely that inflammation-induced epithelial damage is important in determining the ionic composition of the ASL.

Effects of nicotine on intestinal and respiratory epithelium.

The effects of nicotine on intestinal and tracheal mucosa and epithelial cells were studied in vivo and in vitro. Rats received 108 microM nicotine in their drinking water for 10 days. Intestine and trachea were removed and prepared for X-ray microanalysis, transmission electron microscopy and immunocytochemistry. X-ray microanalysis of freeze-dried cryosections of intestine and trachea showed an increase in Na and Cl, and a decrease in K in the lamina propria of the intestine and the epithelial cells and the submucosal compartment of the trachea. Analysis of frozen-hydrated trachea, in order to determine ionic changes in the airway-surface liquid (ASL), indicated that the Na and Cl content in the ASL decreased after nicotine treatment. Immunocytochemistry showed upregulation of ICAM-1 in the submucosal connective tissue of the trachea and the lamina propria of the intestine. Transmission electron microscopy showed a somewhat increased number of eosinophils in the lamina propria of nicotine-treated rats, increased edema in the submucosal connective tissue, and a somewhat increased number of damaged basal cells in the trachea of nicotine-treated rats, compared to the controls. These data indicate that nicotine may evoke an inflammatory reaction, in particular in the trachea, that could cause cell damage and with that changes in the ionic relations of the epithelial cells. The in vitro experiments showed that nicotine could directly affect ion transport by inhibiting cAMP-stimulated (but not ATP-stimulated) chloride efflux from cultured respiratory epithelial cells. This indicates that apart from indirect effects via inflammation, nicotine can directly affect the ionic homeostasis of the cells and the composition of the airway-surface liquid.

Effects of nicotine on intestinal epithelial cells in vivo and in vitro: an X-ray microanalytical study.

It has been suggested that nicotine may have a beneficial effect on ulcerative colitis. Little is known, however, about the mechanism of such an effect. In the present study, the effects of nicotine on intestinal ion transport were investigated by X-ray microanalysis. In addition to an in vivo study, an in vitro system was established by pre-incubating pieces of small intestine in solutions of different ionic composition, in an attempt to stabilize the intracellular ionic composition. It was observed that nicotine caused a loss of Cl (indicative of net chloride efflux) in the villous epithelial cells and the cells of Brunner's glands, in vitro both in Na+ and in K+-containing medium. In in vivo experiments, exposure of mice for 10 days to nicotine in drinking water resulted in a lowering of the cellular chloride concentration in villous epithelial cells of the small intestine, cells of Brunner's glands and epithelial cells of the colon. The results may indicate a disturbance of fluid transport in the intestine by nicotine. Possible mechanisms, such as inhibition of uptake of chloride across the basolateral membrane, are discussed.

Storage of trachea for X-ray microanalytical studies of tracheal submucosal glands.

Pig trachea is a good model system to study airway fluid transport with relevance to human diseases such as cystic fibrosis, since both in pig and in man, the submucosal glands play a quantitatively important role in fluid secretion. Pig trachea can be easily obtained from the local slaughterhouse. In the present study, we investigated the procedure to transport the tissue from the slaughterhouse to the laboratory where physiological experiments can be carried out. Transport of the tissue in a solution with high K+ content (resembling the intracellular environment) maintained the morphology of the glands and a high intracellular K/Na ratio. Physiological experiments can be carried out in solutions with a high Na+ concentration resembling the extracellular environment. The glands secrete chloride on stimulation with alpha-adrenergic, beta-adrenergic, cholinergic and peptidergic agonists. Transport and temporary storage of tissue in high K+ solutions expands the scope of possible X-ray microanalytical studies in the field of pathophysiology.