Adrenergic Receptors and Their Clinical Applications

Adrenergic Receptors

• Adrenergic receptors are a type of G protein-coupled receptor that respond to the neurotransmitter norepinephrine (NE) and the hormone epinephrine (EPI)
• There are two main categories: α (alpha) and β (beta) receptors

Alpha Adrenergic Receptors

• Subtypes: α1, α2
• α1 receptors:
  • Stimulate smooth muscle contraction
  • Increase blood pressure
  • Vasoconstriction
• α2 receptors:
  • Inhibit neurotransmitter release (including NE)
  • Decrease blood pressure
  • Sedation and relaxation

Beta Adrenergic Receptors

• Subtypes: β1, β2, β3
• β1 receptors:
  • Increase heart rate and contractility
  • Stimulate renin release
• β2 receptors:
  • Relax smooth muscle (bronchodilation, vasodilation)
  • Increase glucose release from liver and muscle
• β3 receptors:
  • Lipolysis (breakdown of fat)

Adrenergic Agonists

• Stimulate adrenergic receptors
• Examples:
  • Epinephrine (EPI): non-selective α and β agonist
  • Norepinephrine (NE): non-selective α and β agonist
  • Phenylephrine: selective α1 agonist
  • Isoproterenol: non-selective β agonist
  • Albuterol: selective β2 agonist

Adrenergic Antagonists

• Block adrenergic receptors
• Examples:
  • Phentolamine: non-selective α antagonist
  • Prazosin: selective α1 antagonist
  • Propranolol: non-selective β antagonist
  • Metoprolol: selective β1 antagonist

Clinical Applications

• Treatment of hypertension, angina, and heart failure
• Management of asthma and chronic obstructive pulmonary disease (COPD)
• Anesthesia and surgery
• Treatment of attention deficit hyperactivity disorder (ADHD)

Learn about the types of adrenergic receptors, their functions, and the effects of agonists and antagonists. Understand their clinical applications in treating various medical conditions.