Aerosolized citric acid induces several pulmonary effects including bronchoconstriction, airway inflammation, and cough. Evidence from the use of tachykinin NK1 and NK2 receptor antagonists, as well as chronic treatment with high doses of capsaicin, have suggested that these effects are mediated through the release of tachykinins from sensory nerve endings. In the present study, we have investigated the effects of a tachykinin NK3 receptor antagonist, SR 142801 (osanetant), on cough, bronchoconstriction, and bronchial hyperresponsiveness induced by aerosolized citric acid (0.4 M) in guinea pigs. SR 142801, at 0.3 and 1 mg . kg-1 by intraperitoneal route, significantly inhibited cough in conscious guinea pigs by 57 +/- 3 and 62 +/- 10% (n = 8), respectively. In anaesthetized guinea pigs, it failed to inhibit the bronchoconstriction induced by citric acid when given alone but abolished it when combined with the tachykinin NK2 receptor antagonist, SR 48968 (saredutant). In guinea pigs pretreated with thiorphan (1 mg . kg-1), aerosolized citric acid (0.4 M, 1 h) induced airway hyperresponsiveness 24 h later, displayed by an exaggerated response to the bronchoconstrictor effect of acetylcholine. A microvascular leakage hypersensitivity also occurred and was demonstrated by a potentiation of the plasma protein extravasation from bronchial vessels induced by histamine. When given once intraperitoneally at 1 mg . kg-1 30 min before the citric acid exposure, SR 142801 inhibited both hyperresponsiveness to acetylcholine and the potentiation of histamine-induced increase in microvascular permeability. The results suggest that tachykinin NK3 receptors are involved in citric acid-induced effects on airways.

Compared to two previous studies performed in 1990 and in 1995 in our hospital, the aluminum contamination of parenteral nutrition solutions and the daily aluminum intake of the children seemed to decrease. However, the plasma aluminum concentration and daily urinary aluminum excretion of the children still remain above normal standards. The children had no clinical symptoms of bone disease but aluminum accumulation in tissue can not be excluded. To prevent this iatrogenic toxicity, the aluminum contamination of parenteral nutrition should be assessed regularly.

No abstract