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Sympathetic Nervous System

Sympathetic Nervous System. Nervous System. CNS. PNS. Brain Spinal Cord. Autonomic NS. Somatic NS. Sympathetic. Parasympathetic. CNS. ACh. C. M. N. ACh. T. ACh.  1. NE. N. L. NE.  1.  2. S. ACh. SM. N. CNS. ACh. C. M. N. ACh. T. ACh.  1. NE. N. L. NE.

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Sympathetic Nervous System

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  1. Sympathetic Nervous System

  2. Nervous System CNS PNS Brain Spinal Cord Autonomic NS Somatic NS Sympathetic Parasympathetic

  3. CNS ACh C M N ACh T ACh 1 NE N L NE 1 2 S ACh SM N

  4. CNS ACh C M N ACh T ACh 1 NE N L NE 1 N EPI ACh 2 S ACh SM N

  5. CNS ACh C M N ACh T ACh 1 NE N L NE ACh 1 N SG ACh M 2 S ACh SM N

  6. Sympathetic Nervous System CNS (-) 2 C M T ACh 1 NE N L NE 1 N EPI ACh 2 S

  7. Dual Innervation Exceptions (only sympathetic) - blood vessels (only parasympathetic) - bronchioles (only parasympathetic) - ciliary muscles Predominant Tone Primarily parasympathetic NS Exceptions - blood vessels (sympathetic) - sweat glands (sympathetic cholinergic)

  8. Denervation Supersensitivity + Effect +++ Effect NT NT Before Denervation After Denervation

  9. Catecholamines NE EPI DA

  10. PRESYNAPTIC POSTSYNAPTIC NE - predominately removed from synapse via ‘re-uptake 1’ Metabolic Removal Re-uptake 2 Re-uptake 1 NE synthesis COMT MAO NE  /  Action NE MAO (-) 2 Receptor Binding

  11. Drug actions at presynaptic autonomic nerve terminals

  12. Adrenergic Receptors 1, 2, 1 NE 1, 2, 1, 2 EPI

  13. Adrenergic Receptors 1, 2, 1 NE 1, 2, 1, 2 EPI 1, 1, DA1 DA

  14. EFFECTS OF STIMULATING ADRENERGIC RECEPTORS SITEEFFECT HEART TACHYCARDIA and INCREASED CONTRACTILITY (1) VASCULATURE VASODILATION VASOCONSTRICTION (1,  2) (2) BRONCHORELAXATION (2) AIRWAYS IRIS MYDRIASIS (1) BLADDER DECREASED URINATION (2) GI TRACT DECREASED GI MOTILITY and SECRETIONS (2) UTERUS RELAXATION (2)

  15. contractile force heart rate 1 renin release vasodilation, TPR 2 vasoconstriction TPR 1, 2

  16. Drugs and Adrenergic Synapses

  17. CNS Adrenergic Agonists ACh C M N ACh T ACh 1 NE N L NE 1 N EPI ACh 2 S ACh SM N

  18. MIXED ADRENERGIC AGONISTS • Norepinephrine 1, 2, 1 • Epinephrine 1, 2, 1, 2 Dopamine DA1, 1, 1

  19. HR BP TPR

  20. MIXED ADRENERGIC AGONISTS • Norepinephrine (1, 2, 1) • Epinephrine (1, 2, 1, 2) Tx: ● Asthma (but there are better drugs) ● Anaphylactic shock ● Cardiogenic shock ● Prolong action of local anesthetics ● Topical hemostatic agent Dopamine (DA, 1, 1) Tx: ● CHF

  21. ALPHA AGONISTS - Phenylephrine (1) - Methoxamine (1) • - Oxymetazoline (1 and 2 in periphery) - Tetrahydrozoline (1) - Naphazoline(1) - Ephedrine/Pseudoephedrine (1) • - Clonidine (2, Tx site of action is CNS)

  22. Tx uses for ALPHA AGONISTS • Alpha-1 agonists Tx: ● Nasal decongestion ● Used in eye drops to ‘get the red out’ ●Hypotensive states Alpha-2 agonists Tx: ● Hypertension

  23. BETA AGONISTS and Tx uses Non-selective 1/2 - Isoproterenol Selective 1 • - Dobutamine Selective 2 • - Albuterol Tx: Cardiac stimulant • - Metaproterenol • - Terbutaline Tx: COPD, Asthma • - Isoetharine • - Bitolterol Tx: Inotropic agent • - Ritodrine Tx: Uterine relaxation

  24. NE EPI ISO HR BP TPR

  25. Dose-response effects produced by dopamine at different receptors

  26. CNS ADRENERGIC AGENTS • CNS : Tx antihypertensive effect • - Clonidine(2 agonist) - Guanabenz (2 agonist) - Guanfacine (2 agonist) - Methyldopa Converted in CNS to methylnorepinephrine (low efficacy 2 agonist)

  27. Sympathetic Nervous System CNS (-) 2 C M T ACh 1 (-) NE N (-) L NE 1 N EPI ACh 2 S 2

  28. CNS Adrenergic Antagonists ACh C M N ACh T ACh 1 X NE N L X NE 1 N EPI X ACh 2 S ACh SM N

  29. ALPHA ANTAGONISTS and Tx uses Nonselective 1 and 2 receptor antagonists - Phenoxybenzamine Non-competitive action • - Phentolamine Competitive action Tx: - DOC for overdose of alpha agonists - Management of pheochromocytoma - Dental use for reversal of local anesthetic action Selective 1 receptor antagonists - Prazosin - Terazosin(water soluble) Tx: Antihypertensive agents, Management of benign prostatic hypertrophy

  30. Adrenergic Influence on Vascular Smooth Muscle Tone VSMC 2 NE 1 NE Vasoconstriction (-) 2

  31. Adrenergic Influence on Vascular Smooth Muscle Tone EPI VSMC 2 Vasoconstriction NE 1 NE Vasoconstriction (-) 2

  32. Marked hypotensive response produced by dual 1 and 2 - Receptor Blockade on VSMC EPI VSMC X 2 Vasodilation X NE NE 1 Vasodilation (-) X 2 Phentolamine- 1 and 2 blockade

  33. Moderate hypotensive response produced by dual 1 and 2 - Receptor Blockade 0n VSMC EPI VSMC 2 Vasoconstriction X NE NE 1 Vasodilation (-) 2 Prazosin- selective 1 blockade

  34. BETA ANTAGONISTS ● Non-selective 1, 2 ● ‘Cardio’- Selective 1 • Atenolol • Propranolol • Metropolol Nadolol Esmolol Timolol Acebutolol(ISA) Pindolol ● Non-selective 1, 2, 1 Carteolol Intrinsic Sympathomimetic Activity Labetalol Carvedilol

  35. Beta Blocker Tx Uses: ●Congestive heart failure ● Hypertension ● Myocardial infarction ●Angina ●Migrane ● Arrhythmias ●Anxiety ●Stage fright

  36. INDIRECT ACTING ADRENERGIC AGONISTS Tyramine(dietary substance) Ephedrine Pseudoephedrine Amphetamine

  37. Amphetamine PRESYNAPTIC POSTSYNAPTIC Re-uptake 1 NE  /  Action NE Receptor Binding

  38. Amphetamine PRESYNAPTIC POSTSYNAPTIC Re-uptake 1 amphetamine NE NE (+)  /  Action Receptor Binding

  39. Uptake Blockers • Cocaine • Tricyclic Antidepressants

  40. Cocaine PRESYNAPTIC POSTSYNAPTIC Re-uptake 1 NE  /  Action NE Receptor Binding

  41. Cocaine PRESYNAPTIC POSTSYNAPTIC Re-uptake 1 cocaine X NE NE  /  Action Receptor Binding

  42. Neuronal Blockers • Reserpine Depletes NE stores by inhibiting vesicular uptake of NE; NE then metabolized by intra-neuronal MAO • Guanethadine Inhibits NE release, also causes NE depletion, and can damage NE neurons

  43. Monoamine Oxidase (MAO) Inhibitors • Pargyline • Tranylcypromine Tyramine (or other drugs that promote NE release) may cause markedly increased blood pressure in patients taking MAO inhibitors

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