Autonomic drug concepts Flashcards
what neurotransmitter is used in presynaptic neurons?
achetylcholine
what neurotransmitter is used in postsynaptic PNS neurons?
acetylcholine
what neurotransmitter is used in postsynaptic SNS neurons?
norepinephrine (or acetylcholine)
what neurotransmitter is used in somatic neurons?
acetylcholine
what neurotransmitter receptors are at SNS tissues?
adrenergic, muscarinic (sweat glands)
what neurotransmitter receptors are at PNS tissues?
muscarinic
what neurotransmitter receptors are at somatic tissues?
nicotinic
which cranial nerves have parasympathetic neurons?
III (smooth muscles of the eye)
VII (lacrimal glands)
IX (salivary glands)
X (smooth muscles in abdominal + thoracic viscera)
what receptors are at ANS synpases?
nicotinic neuronal
what kind of receptors are muscarinic receptors?
GPCR
what kind of receptors are nicotinic receptors?
ligand-gated ion channels (need 2 Ach molecules to open)
where are M1 receptors?
CNS
autonomic ganglia
glands (secretion of gastric juice)
enteric nerves
where are M2 receptors?
CNS
heart (slows heart rate and conduction at SA/AV nodes, and slows force of contraction)
smooth muscle
autonomic nerve terminals
where are M3 receptors?
CNS
smooth muscle (contraction at iris, bronchi, GI tract)
glands
heart
where are N_m receptors?
neuromuscular junction (opens Na/K channels for contraction)
where are N_n receptors
autonomic ganglia adrenal medulla (secretion of catecholamines) CNS
mechanism of action for M1,M3,M5 receptors (stimulatory)
G_q -> PLC -> PIP -> IP3 -> DAG -> PKC
mechanism of action for M2,M4 receptors (inhibitory)
inhibition of adenylate cyclase -> decreased cAMP
activation of inward rectifying potassium channels so hyperpolarization
inhibition of neuronal calcium channels
what are the effects of nicotine?
stimulation: sympathetic ganglia, parasympathetic ganglia, blockade of parasympathetic ganglia
adrenal medulla: epi release
supraoptic nucleus: release ADH
CNS: tremor and nausea
what are the effects of nicotinic receptor antagonists
primarily: non-depolarizing (competitive) neuromuscular blockade
what are the effects of non depolarizing blockers at low dose? at high dose?
low: blocks receptor
hi: enters pore of receptor; hard to reverse
what are the effects of depolarizing blockers? (2 phases)
phase I: cause release, hard to repolarize
phase II: desensitization after repolarization
where are endogenous catecholamines made?
in the sympathetic nerve endings and chromaffin cells of the adrenal medulla
name the steps (starting at tyrosine) of catecholamine synthesis
tyrosine, DOPA, dopamine, norepinephrine, epinephrine
where are alpha 1 receptors found?
VSMC, genitourinary SMC, intestinal SMC, heart, liver
where are alpha 2 receptors found?
pancreatic beta cells, platelets, nerves, VSMCs
what do alpha 2 agonists activate?
G_i for decreased adenylyl cyclase. inhibit some channels and inhibit release
where are beta 1 receptors found?
heart (hi chronotropy and inotropy and AV node conduction velocity)
renal JGA cells (more renin)
G_s
where are beta 2 receptors found?
smooth muscle (mostly pulmonary and peripheral; relaxation), skeletal muscle, liver (glycogenolysis) G_s
where are beta 3 receptors found?
adipose (lipolysis)
Which receptors does norepinephrine act on?
a1,a2,b1,b2,b3
What is reflex bradycardia?
When baroreceptors sense an increase in the pressure, activates vagus nerve, and decreases HR via Ach release to M2 receptors
Which receptors does epinephrine act on?
a1,a2,b1,b2,b3
Higher beta effect at low doses, and vice versa
How does dopamine cause vasodilation?
D2 receptors inhibit AC -> low cAMP
What are the effects of dopamine?
Vasodilation low dose B1 effects high dose A1 effects (vasoconstrict) high dose
two uses of a1 adrenergic agonists?
treatment of shock
topically in nasal decongestant
difference between a1 and a2 receptors?
a1 is activating, a2 is inhibiting (inhibit adenylyl cyclase)
use of a b1 selective agonist?
increase cardiac output
use of a b2 selective agonist?
relaxation of bronchial smooth muscle
