Neurotransmission and Second Messengers

Neurotransmission and Second Messengers

1. Calcium

   • Release vesicles
   • Muscle contraction
   • Regulating blood flow
   • Platelet functioning
   • Activation of the clotting cascade

2. Metabolism of NE

   • Catechol-O-methyl transferase (COMT)
   • Monamine oxidase (MAO)

3. Noradrenergic receptors

   • Alpha 1: vascular smooth muscle contraction (vasoconstriction)
   • Alpha 2
     • Inhibit NE release
     • Inhibit NE-mediated vasoconstriction
   • Beta 1
     • Increase heart rate
     • Increased myocardial contractility
   • Beta 2
     • Vasodilation
     • Bronchodilation

4. Muscarinic receptors

   • M1
     • Enteric nervous system
     • Rest and digest
   • M2: decrease contractility and heart rate in the atria at the SA node
   • M3
     • Increase bladder contraction
     • Increase gut peristalsis
     • Lacrimation or tearing
     • Miosis
     • Bronchoconstriction

5. Dopamine receptors

   • D1: relax renal vascular smooth muscle
   • D2: found in the brain

6. Histamine receptors

   • H1
     • Allergy symptoms
     • Pruritus
     • Bronchoconstriction
   • H2: increase gastric acid secretion

7. ADH receptors

   • V1: increase vascular smooth muscle contraction
   • V2: increase reabsorption in collecting tubules of the kidney

8. G-protein second messengers

   • Alpha: Epi and NE
   • Beta: Epi and NE
   • M: ACh
   • D1, D2: dopamine
   • H1, H2: histamine
   • V1, V2: vasopressin