Role of surfactant in alveolar defence against inhaled particles.

Alveolar surfactant molecules may concentrate on particulated matter (powders or microbes) with the formation of liposomes. In vitro the spraying of powders on a surfactant film causes the appearance of liposomes and consequent alterations in the tension/area diagram. In animals soon after inhalation of powders fine enough to be deposited in alveoli surfactant liposomes containing powder particles are observed in the alveolar spaces and later on along the airways. The powder content of liposomes collected through a T cannula in the trachea may be demonstrated by chemical or electronic microscopical analysis. Prolonged inhalation of powder may induce surfactant depletion and alveolar bronchiolar instability. In mice exposed for 5 months to silica dust a correlation has been found between surfactant depletion and silica retention in the lung with recruitment of phagocytic cells and increased serum and BAL-lysosomal enzyme activity. In animals treated with ambroxol, the clearance of silica is faster and longer lasting, and the pulmonary alterations are delayed and reduced. The first results of clinical trials with ambroxol in miners seem favorable. Microbes may also be incorporated as powder particles in alveolar surfactant liposomes. Using motile strains, bacteria struggling within a liposome may be observed with a telecamera. Preliminary observations suggest a direct antimicrobial action of ambroxol.

[The effect of unintentional overdoses of pilocarpine on pulmonary surfactant in mice]. / Die Wirkung akzidenteller Uberdosierung von Pilocarpin auf den pulmonalen Surfaktant an der Maus.

Pilocarpine, used in the treatment of glaucoma, shows basically parasympathomimetic activities and in contrast to choline derivatives an extremely potent effect on salivary and sweat glands and a noticeable increase of bronchial secretion. Investigations were carried out in mice to determine whether the administration of pilocarpine results in an increase of bronchial secretion as such or whether it likewise influences the secretion of surfactant, i.e., the phospholipoprotein responsible for the stability of the alveoli. Our experiments (P/V diagrams and histochemical staining) demonstrate that pilocarpine decreases the secretion of pulmonary surfactant. When pilocarpine and Ambroxol are administered the effects on the two parameters are similar to the controls. In other words, Ambroxol increases the secretion of surfactant even in cases of intoxication with pilocarpine.

[Therapeutic study on ambroxol in chronic bronchopulmonary diseases (author's transl)]. / Therapeutische Studie mit Ambroxol bei chronisch bronchopulmonalen Erkrankungen.

The clinical activity of trans-4-[(2-amino-3,5-dibromo-benzyl)-amino]-cyclohexanol-hydrochloride (ambroxol, NA 872) as well as its influence on lung function was examined in a total of 63 patients (34 suffering from silicosis, 28 from chronic obstructive bronchitis and 1 from cryptococcosis). Additionally, the content of phospholipids was controlled in the sputum of the patient group. It was shown that the activity of ambroxol was better in the silicosis group than in the bronchitis group. The cause was discussed. Presumably the twofold site of action in the silicosis group (secretolysis and surfactant stimulation) might be the reason for this.