USMLE

Beta-2 (Adrenergic) Receptors

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General Pharm
  1. Gs / Gi Pathway
  2. Gq Signaling Pathway
  3. Alpha-1 (Adrenergic) Receptors
  4. Alpha-2 (Adrenergic) Receptors
  5. Beta-1 (Adrenergic) Receptors
  6. Beta-2 (Adrenergic) Receptors
  7. Beta-3 (Adrenergic) Receptors
  8. M1 (Muscarinic) Receptors
  9. M2 (Muscarinic) Receptors
  10. M3 (Muscarinic) Receptors
  11. D1 (Dopamine) Receptors
  12. D2 (Dopamine) Receptors
  13. H1 (Histamine) Receptors
  14. H2 (Histamine) Receptors
  15. V1 (Vasopressin) Receptors
  16. V2 (Vasopressin) Receptors

Summary

Beta-2 receptors are adrenergic receptors coupled to a Gs protein subunit. When activated, one of their main downstream effects is the phosphorylation and inactivation of MLCK. Inactivation of MLCK leads to bronchodilation, vasodilation, and decreased uterine tone,  all of which are seen in beta-2 receptor activation. Beta-2 receptors are also found in the ciliary process and ciliary muscle of the eye, and beta-2 activation leads to increased aqueous humor production and reduced outflow. Finally, beta-2 receptor activation can also increase potassium uptake and increase insulin release.

Key Points

  • Beta-2 Receptors
    • Signaling
      • Use the Gs signaling pathway
    • Outcomes
      • Bronchodilation
      • Increased aqueous humour production
      • Increased insulin release
      • Decreased uterine tone
      • Increased K+ uptake