Figure 5.

Stimulated secretory activity after 25 days of exposure to 5, 10, 20, 40 ppm SO2 or fresh air and 20 days exposure to 80 ppm SO2. The acetylcholine-stimulated secretory activity of rat tracheas (for each group n = 4) was assessed by the modified Ussing Chamber technique. Results are presented as mean ± SD cpm. ** indicates p < 0.01