6- Cholinergic Physiology Review Flashcards
choline is transported from the extracellular fluid into the neuron terminal by ….
choline transporter CHT
what inhibits CHT?
hemicholiniums
in the cytoplasm, Ach is synthesized from choline and acetyl Co A by …
choline acetyltransferase ChAT
Ach is transported into storage vesicle by …
vesicle associated transporter VAT
what inhibits VAT
vesamicol
vesicles full of ACH are concentrated on the inner surface of n. terminals by the actions of _________ on vesicle and _________ on cell membrane
v-SNAREs (synaptobrevin)
t-SNAREs (syntacin and SNAP-25)
are vesamicol and hemicholiniums prescription drugs?
No - too strong for clinical use. but they are used in research
where do botulinum toxins work?
prevent the release of the Ach vesicle
Ach’s action is terminated rapidly via metabolism by _______
acetylcholinesterase AchE
AchE inhibitors
anticholinesterases
ex: neostigmine enhances effects of Ach
two different cholinoreceptors
- muscarinic M (gprtn receptors)
- nicotinic N (ion channels - alpha subunit)
signal transduction of M1 and M3 receptors
Phospholipase C pathway with IP3 and DAG leading to increase in calcium and Prtn kinase C
signal transduction of M2 receptors
adenyly cyclase to decrease cAMP and decrease PKA
effects of muscarinic receptors on sphincter muscle of eye
binds to M3 receptor
causes contraction and opening of canal of Schlemm
effects of muscarinic receptors of ciliary muscle of eye
binds to M3 receptor
accomodation for near vision
effects of muscarinic receptors on SA node
binds to M2 receptor
decreases HR via negative chronotropy
effects of muscarinic receptors on AV node
binds to M2 receptor
decrease conduction velocity via negative dromotropy
what happens to ventricular contraction with muscarinic receptor activation?
decreased ventricular contraction
no effects on ventricles of purkinje system
effects of muscarinic receptors on bronchioles
binds to M3 receptor
causes contraction - bronchospasm
effects of muscarinic receptors on glands in lungs
secretion (narrows lumen)
effects of muscarinic receptors in stomach
binds to M3 receptor
increases motility, cramps
effects of muscarinic receptors in glands of GI tract
binds to M1/3
increases secretion
effects of muscarinic receptors in intestine
binds to M3 receptors
causes contraction - diarrhea, involuntary defecation
effects of muscarinic receptors on bladder
binds to M3 receptors
contraction (detrusor) and relaxation of trigone/sphincter –> voiding, urinary incontinence
effects of muscarinic receptors on sphincters
binds to M3 receptors
causes relaxation
what is the only sphincter which contracts with activation of M3 receptors?
lower esophageal sphincter
effects of muscarinic receptors on glands
binds to M3 receptors
secretion - sweat (thermoregulatory), salivation, and lacrimation
effects of muscarinic receptors on blood vessels
binds M3 receptors
dilation (EDRF)
how do M1 and M3 work in glands of GI tract
M3 receptors are on parietal cells are directly activates to secrete acid
M1 receptors activated histamine secretion which also stimulates acid secretion
when the endothelium is damaged… drect effect of M3 activation on VSMC causes…
vasoconstriction
normally M3 causes vasodilation
adrenal medulla response to nicotinic receptor activation
Nn receptor
secretion of epinephrine and Ne
autonomic ganglia response to nicotinic receptor activation
Nn receptor
stimulation - net effects dependent of PANS/SANS innervation and dominance
neuromuscular junction response to nicotinic receptor activation
Nm receptor
stimulation - twitch/hyperactivty of skeletal muscle
