Figure 2.

The effect of exposure (90 min) to medi-air (0.35 l min⁻¹), or medi-air via an ozone generator (2.15±0.05 p.p.m.) with and without dexamethasone (20 mg kg⁻¹) or rolipram (1 mg kg⁻¹) treatment on respiratory rate, in conscious guinea-pigs. Treatment was administered 24 and 0.5 h before exposure to ozone and 24 h afterwards. Each point represents the mean±s.e.mean (n=6) change in respiratory rate (breaths min⁻¹). Black bar denotes the significance of differences (P<0.05) between respiratory rate before and after exposure to ozone as determined by analysis of variance (single factor), followed by Student's unpaired t-test. There was no significant (P>0.05) difference between the respiratory rate in ozone exposed guinea-pigs with and without rolipram, dexamethasone or vehicle (data not shown) treatment.