The effects of β-adrenoceptor blockade on lung function

In the graph below, data for atenolol and placebo are taken from the collated practical classes in 2022, while data for pindolol was obtained from a previous cohort of students.

Figure 5: The effect of β-adrenoceptor antagonists on resting peak expiratory flow rate (PEFR) of healthy individuals over time. Placebo (vitamin B6, 10 mg), atenolol (50 mg) or pindolol (10 mg) were administered at 0 min. Data shown as mean ± s.e.m. * p<0.05 drug vs placebo (ANOVA); n = 41-73 per treatment.

Briefly describe the data shown.