[Investigation of the mucociliary clearance by means of 99mTc-labelled sulfur colloid (author's transl)].

The mucociliary system of the lung was studied in eight normal subjects and ten patients with chronic bronchitis, using sulfur colloids, labelled with 99mTechnetium. By recording the radioactive impulses over the lung with a scintillation camera and analysing the data with a computer, we were able to exclude extrapulmonary artefacts and to select central areas of the tracheobronchial tree. Time activity curves obtained over the central airways were interpreted by means of a model. In bronchitics the disappearance rate of the radioactive particles was found to depend upon the pattern of deposition and the degress of airway obstruction. Because of the good reproducibility in one and the same subject, the effect of drugs, influencing the mucociliary system, can be tested. We used a newly developed vagolytic substance which did not influence the mucociliary system and which reduced little the airway resistance in patients with chronic bronchitis at the administered dose.