The effects of β-adrenoceptor blockade on blood pressure at rest

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 3: The effect of β-adrenoceptor antagonists on resting systolic blood pressure 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. mmHg, millimetre of mercury.

Is this result expected? Explain why or why not.