Description of the different study protocols
| Protocol number | Drugs used | Route of administration | Doses mg·kg−1 | Days of administration |
| Assessment of airway inflammation | ||||
| 1 | DMPP | i.p. | 0.01–0.5 | 21, 22, 23 |
| 2A | DMPP | i.p. | 0.5 | 1–20 |
| 2B | DMPP | i.p. | 0.5 | 21, 22, 23 |
| 2C | DMPP | i.p. | 0.5 | 1–23 |
| 3A | DMPP | i.n. | 2 | 21–23; 24# |
| 3B | DEXA | i.n. | 2 | 21–23; 24# |
| Assessment of airway resistance | ||||
| 4 | DMPP | i.n. | 0.5 | 24# |
| 5 | DMPP | i.n. | 0.5 | 21–23; 24# |
| 6A | DMPP | i.n. | 2 | 21–23; 24# |
| 6B | DEXA | i.n. | 2 | 21–23; 24# |
DMPP: 1,1-dimethyl-4-phenylpiperazinium; DEXA: dexamethasone; i.p.: intraperitoneally; i.n.: intranasally. #: 10 min prior to metacholine test.