What effect does pilocarpine have on heart rate?

Pilocarpine is a muscarinic agonist, meaning it stimulates the parasympathetic nervous system, which is responsible for the "rest and digest" responses in the body. When pilocarpine is administered, it activates the receptors that can lead to a decrease in heart rate, often referred to as bradycardia.

Under normal physiological conditions, the parasympathetic nervous system opposes the effects of the sympathetic nervous system, which tends to increase heart rate and cardiac output. By enhancing the actions of the parasympathetic nervous system, pilocarpine reduces the firing rate of the sinoatrial (SA) node, the natural pacemaker of the heart, leading to a lower heart rate.

This decrease in heart rate can be particularly beneficial in situations where reducing cardiac workload is necessary or when managing certain medical conditions that feature an accelerated heart rate. Therefore, the correct answer accurately describes the pharmacological effect of pilocarpine on heart rate.