Principles: Autonomic Principles and Receptors Flashcards
What are nicotinic receptors?
Where are they located, what are the subtypes?
Nicotinic receptors are ligand-gated Na+/K+ channels activated by ACh.
NN: Found in autonomic ganglia
NM: Found in neuromuscular junction
What are muscarinic receptors?
Subtypes?
Muscarinic ACh receptors: G-protein-coupled receptors. Usually act through second messengers.
M1, M2, M3, M4, M5
What effect to Gs proteins have?
Activate adenylyl cyclase, increase cAMP, activate Protein Kinase A
PKA increases intracellular calcium in the heart (activating) and
Inhibits myosin light-chain kinase in smooth muscle - causing relaxation
What effect to Gi proteins have?
Inhibit adenylyl cyclase, decrease cAMP production, reduce activation of Protein Kinase A
Oppose actions of Gs
ACRONYM: MAD 2’s: M2, α2, and D2 are the Gi receptors.
What effect do Gq receptors have?
Activate Phospholipase C
Cleave PIP2 into DAG and IP3
DAG directly activates Protein Kinase C
IP3 increases intracellular calcium.
ACRONYM: HAVe 1 M&M:
H1, α1, V1,
M1, and M3 are all Gq.
What type of G-protein is the α1 receptor? What nervous system does it belong to?
What are its major functions?
Sympathetic nervous system, Gq
Induces vascular smooth muscle contraction, pupillary dilator muscle contraction (mydriasis), and intestinal and bladder sphincter muscle contraction.
What type of G-protein is the α2 receptor? What nervous system does it belong to?
What are its major functions?
Sympathetic nervous system, Gi receptor.
Inhibits sympathetic outflow, decreases insulin release and lipolysis, induces platelet aggregation.
What type of G-protein is the β1 receptor? What nervous system does it belong to?
What are its major functions?
Sympathetic, Gs
Increases heart rate, contractility, renin release, and lipolysis.
What type of G-protein is the β2 receptor? What nervous system does it belong to?
What are its major functions?
Sympathetic, Gs receptor.
Induces vasodilation, bronchodilation, increases heart rate and contractility, increases lipolysis, insulin production, and aqueous humor production, and reduces uterine tone (tocolysis) and relaxes the ciliary muscle.
What type of G-protein is the M1 receptor? What nervous system does it belong to?
What are its major functions?
Parasympathetic nervous system, Gq.
Activity in the CNS and enteric nervous system.
What type of G-protein is the M2 receptor? What nervous system does it belong to?
What are its major functions?
Parasympathetic, Gi
Reduces heart rate and contractility of the atria.
What type of G-protein is the M3 receptor? What nervous system does it belong to?
What are its major functions?
Parasympathetic, Gq receptor.
Induces exocrine gland secretions (lacrimal, salivary, gastric acid)
Induces gut peristalsis
Induces bladder contraction and bronchoconstriction
Induces pupillary sphincter muscle contraction (miosis) and ciliary muscle contraction (accomodation)
What type of G-protein is the D1 receptor?
What are its major functions?
Gs
Relaxes renal vascular smooth muscle.
What type of G-protein is the D2 receptor?
What are its major functions?
Gi receptor.
Modulates transmitter release, especially in the brain.
What type of G-protein is the H1 receptor?
What are its major functions?
Gq receptor.
Increases nasal and bronchial mucous production
Increases vascular permeability
Induces contraction of bronchioles, pruritis, and pain
