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INTRODUCTION TO AUTONOMIC PHARMACOLOGY: Part III Mechanism of neurotransmission at in the autonomic nervous system. General Features of Peripheral Autonomic Neurotransmission. NT = Neurotransmitter. General Features of Peripheral Autonomic Neurotransmission.
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INTRODUCTION TO AUTONOMIC PHARMACOLOGY: Part III Mechanism of neurotransmission at in the autonomic nervous system
General Features of Peripheral Autonomic Neurotransmission NT = Neurotransmitter
General Features of Peripheral Autonomic Neurotransmission Depolarization of Postganglionic Fiber or Response of Effector Cell Nerve Impulse Membrane Depolarization of Pre- or Postganglionic Fiber Activation of NT Receptors Calcium Entry into Varicosity Diffusion of NT Across Neuroeffector Junction or Synapse Exocytosis of NT
SUMMARY OF ADRENERGIC NEUROTRANSMISSSION COMT Effector Cell Sympathetic Postganglionic Fiber NeuroeffectorJunction (Liver)
Summary of Catecholamine Biosynthesis Tyrosine DOPA Dopamine SYMPATHETIC NERVE Norepinephrine ADRENAL GLAND Epinephrine
SUMMARY OF CHOLINERGIC NEUROTRANSMISSSION Neuroeffector Junction Parasympathetic or Sympathetic Postganglionic Fiber or Effector Cell Parasympathetic/Sympathetic Preganglionic Fiber or Parasympathetic Postganglionic Fiber
COTRANSMISSION Release of More Than One Neurotransmitter from the Same Nerve Terminal Cotransmitter A Cotransmitter B Synergistic or Opposite Actions
Types of Postsynaptic Synergism Norepinephrine/NPY Norepinephrine/ATP
Example of Postsynaptic Synergism: (NPY enhances actions of NE) Perfusion Pressure (mmHg) NPY 10 nM NE NE
Example of Postsynaptic Synergism: ATP mediates fast response NE mediates slow response Control Prazosin Prazosin + Suramin Control Suramin Prazosin + Suramin
MODULATION OF NEUROTRANSMISSION Modulation of Neurotransmisson Presynaptic/ Postsynaptic/ Prejunctional Postjunctional Modulation Modulation Presynaptic/ Postsynaptic/ Prejunctional Postjunctional Inhibition Inhibition Postsynaptic/ Presynaptic/ Prejunctional Postjunctional Facilitation Facilitation
MODULATION OF NEUROTRANSMISSION Sources of Modulators of Neurotransmission From Nerve Terminal Being From Modulated Postsynaptic/ (e.g., Postjunctional Autoinhibitory Site (e.g., Trans- From Feedback) synaptic/ Nearby Transjunctional Nerve From Inhibitory Terminal Remote Feedback) (Cross- Site via talk) Circulation (e.g., Renin Release)
Mechanisms of Neuromodulation NE NE Ach + Ang II