[The broncholytic effect of buffers applied by inhalation. A new pharmacological concept (author's transl)]

A new method was developed by which the tone of bronchial smooth muscle can be measured breath by breath in man. Thereby state and reactions of bronchial smooth muscle can be studied. Former investigations had shown that carbonic anhydrase inhibitors have a broncholytic effect. The mechanism of action presumably is the prevention by carbonic anhydrase inhibitors of CO2 induced changes of pH within the bronchial epithelium occurring breath by breath with different partial pressures of CO2. Principally a stabilisation of pH can also be achieved by buffers. Therefore the broncholytic effect of buffers was tested and a 10% buffer solution of phosphat and Tris (THAM) buffer applied by inhalation in two healthy volunteers. In both cases a significant bronchodilation was seen, which in case of phosphate was substantially greater than in case of conventional broncholytics (e.g., fenoterol). As concerns onset and duration of the broncholytic effect, buffers are similar to conventional broncholytics. It is great advantage that buffers do not stimulate bronchial peristalsis and do not have cardiac side effects, contrary to conventional broncholytics.