The effects of β-adrenoceptor blockade on resting heart rate.

Figure 1: The effect of β-adrenoceptor antagonists on resting heart rate 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. Bpm, beats per minute.

In the practical class, you learned that β-adrenoceptor blockade should have no effect on resting heart rate. What may have caused the decrease in heart rate seen here?  

The effects of β-adrenoceptor blockade on resting heart rate

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 1: The effect of β-adrenoceptor antagonists on the resting heart rate 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. Bpm, beats per minute.

Briefly describe the data shown.

The effects of β-adrenoceptor blockade on heart rate

Now, predict the effect of β-adrenoceptor blockade on heart rate at rest and during exercise

The effects of exercise on the cardiovascular system and the autonomic nervous system

Predict how exercise (or stress) affects each of the parameters below.