Jackson (Tier 1): Adrenergic Agonists and Antagonists

Where do adrenergic drugs act within the nervous system?

Sympathetic division of the autonomic nervous system

What are adrenergic agonists (sympathomimetics)?

Drugs that stimulate the SNS by mimicking norepinephrine and/or epinephrine

What are adrenergic antagonists (sympatholytics)?

Drugs that bind adrenergic receptors and block SNS stimulation

What are the major adrenergic receptor types?

α1, α2, β1, β2, and β3

What is the major function of α1 receptors?

Smooth muscle contraction

What is the major function of α2 receptors?

Negative feedback that decreases norepinephrine release

What is the major function of β1 receptors?

Cardiovascular stimulation

What is the major function of β2 receptors?

Bronchodilation and vasodilation

What is the major function of β3 receptors?

Lipolysis

Where are α1 receptors primarily located?

Postsynaptic effector cells

Where are α2 receptors primarily located?

Presynaptic nerve terminals

What is the effect of β1 stimulation on the heart?

↑ heart rate and contractility

What is the effect of β2 stimulation on bronchial smooth muscle?

Relaxation → bronchodilation

How does a direct-acting sympathomimetic work?

Binds directly to an adrenergic receptor and produces a physiologic response

How does an indirect-acting sympathomimetic work?

Causes release of catecholamines from vesicles in nerve endings

How does a mixed-acting sympathomimetic work?

Directly stimulates adrenergic receptors AND causes release of stored catecholamines

What is the fundamental difference between adrenergic agonists and antagonists?

Agonists stimulate adrenergic activity; antagonists block adrenergic activity