Pharmacology Synopses 2 Flashcards
Acetyl CoA + Choline via choline acetyl transferase
Ach
ratelimiting step in Ach formation
availability of choline
excitation by increasing Na+ and K+ conductances
Ach in skeletal muscle
excitation by increasing Na+ conductances
Ach in smooth muscle
inhibition (slowing heartbeat) by increasing K+ conductances
Ach in cardiac muscle
Acetylcholinesterase
hydrolyzes Ach at postsynaptic membrane
Butyrocholine esterase
metabolizes Ach analogs in blood and liver
250 kDa multimeric glycoprotein, related to other ionopore receptors (GABAa)
nicotinic Ach receptor
80 kDa monomeric glycoprotein, related to G-protein coupled receptors like beta-adrenergic
muscarinic Ach receptor
skeletal muscle neuromuscular junction receptor type
Ach nicotinic
main preganglionic to postganglionic synapses receptor type
Ach nicotinic
all parasympathetic postganglionic cells
Ach, muscarinic
____ are primary agents for autonomic ganglia, ____ are only effective as adjuncts
nicotinic, muscarinic
parasympathetic effects: eye
miosis (constriction of pupil)
parasympathetic effects:heart
decrease in heart rate
parasympathetic effects: GI tract
increase motility and tone
parasympathetic effects: bladder
contraction
parasympathetic effects: glands (sweat, lacrimal, nasopharyngeal, etc)
increased secretion (*sweat glands receive cholinergic sympathetic innervation)
parasympathetic effects: adrenal medulla
none, but receives direct Ach nicotinic pre-ganglionic innervation
tissues without nerves, but with muscarinic receptors (many vascular beds)
Ach causes vasodilation
autonomic effects of parasympathetic system, CNS (if passes blood-brain barrier), slow modulatory electrophysiological effects
muscarinic Ach receptor
autonomic ganglia and skeletal muscle, symapthetics & parasympathetics, fast electrophysiological effects
nicotinic Ach receptor
comes from adrenal medulla chromaffin cells, 10-20% of amines secreted
norepinephrine
comes from adrenal medulla chromaffin cells, 80-90% of amines secreted
epinephrin
50% of catecholamine content of CNS mammals, interneurons in some sympathetic ganglia
dopamine
rate limiting step in catecholamine production
tyrosine to DOPA via tyrosine hydroxylase
Pumps 90% norepi into storage vesicles
vesicular monoamine transporter (VMAT-2)
norepi in axoplasm does what?
regulates synthesis
takes most NE released from nerves back up into the synaptic terminal
norepinephrine transporter (NET). NET also transports DA and E.
Cocaine and imipramine (tricyclic antidepressant) inhibit
NET
take synaptic NE into other cells
OCTs (organic cation transporters)
metabolize NE in other cells
COMT (catechol-O-methyltransferase)
members of g-protein-linked receptor family, 7 transmembrane passes
adrenergic receptors
Alpha 1 tissues
vascular smooth muscle, liver
Alpha 1 responses
contraction in vascular smooth muscle, glycogenolysis and gluconeogenesis in liver
Alpha 2 tissues
Nerve terminals, vascular smooth muscle
Alpha 2 responses
decreased release of NE in terminals, contraction in vascular smooth muscles
Beta 1 tissues
Heart
Beta 1 responses
increases force and rate of contraction, AV nodal conduction velocity
Beta 2 tissues
smooth muscle (VASCULAR, bronchial, GI and GU), liver
Beta 2 responses
relaxation in smooth muscle, glycogenolysis and gluconeogenesis in liver
act at sympathetic and parasympathetic ganglia, skeletal muscle and perhaps CNS
nicotinic agonists (and antagonists)
structural similarity to Ach allows binding and blocking of AchE
anticholinesterase mode of action
Anti-ACHEs act
at both nicotinic and muscarinic cites
autonomic effects in order of appearance by dose of muscarinic antagonists
- decreased salivation and sweating. 2. pupil dilation and heart rate increase 3. inhibit micturition, decrease gut motility 4. inhibit gastric secretion
CNS effects of muscarinic antagonists
scopolamine causes drowsiness, amnesia, etc. in clinical doses, excitement, restlessness and hallucination in higher doses. atropine has none
subtype specific: M1
brain (cognition)
subtype specific: M2
Heart
subtype specific: M3
eye
subtype specific: M1/3
salivary glands
subtype specific M2/3
GI tract and bladder
Epinephrin stimulates which receptors
All adrenergic!
Give epi how?
IM or SC, since PO gets degraded in the GI tract by MAO or COMT.
IV epi is dangerous to hypertensive and hyperthyroid because
increases BP (via alpha 1) → cerebral hemorrhage, and increases HR (via beta 1) leads to arrhythmia
reflex brachycardia pronounced with NORepi why?
no beta 2 means no skeletal vasodilation to counteract splanchnic vasoconstriction of alpha 1: increased blood pressure
Are MASTs broken down by COMT?
No. That is why they have a longer half-life
Tyramine (from wine and cheese) + MAO inhibitor
hypertensive crisis due to release of NE stores.
amphetamine, methamphetamine, and cocaine
block NE reuptake
reliance on stored NE causes ____ with meth, tyramine and amphetamine
tachyphylaxis
epi reversal
give epi with alpha antagonists, so only beta effects are agonized.
responsible for BP increase upon standing
Alpha 1, so you’ll faint if it is inhibited
blocks alpha 2 only, increases sympathetic tone, HR and BP
Yohimbine (opposite of clonidine)
SA node location
at the junction of the SVC and right atrium
the only way the impulse can get to the ventricle
through AV node and His bundle
After His, impulse enters ___ and propagates through ventricles
Purkinje cells
Does SA node have resting potential?
No. Self-excites.
sinus node has special pacemaker cells that pass current from out to in, creating
funny current
Like SA, AV node depolarizes due to
inward Ca current
Ca current is slow, allowing what
atria to empty into ventricles before ventricles contract
What causes contraction?
Inward Ca current (Ca–>SR–>releases Ca–>contraction)
P on EKG
atrial polarization
QRS on EKG
ventricular depolarization
T on EKG
repolarization
innervate sinus node, atria, and are not in ventricles
parasympathetics
four ways to change heart rate
level of max diastolic potential, rate of funny current, change threshold potential, change slope of pacemaker current via SA node
sympathetic (adrenergic to beta 1) effects on SA node
increases slope of funny current, membrane depolarizes faster, HR increases
parasympathetic effects on SA node
decrease pacemaker current, slow down rate of polarization, decrease HR
sympathetics on AV node
increase inward Ca current, increase nodal action potential, faster conduction
parasympathetics on AV node
decrease AV nodal action potential, slower conductoin
P w/o QRS
AV block, extreme parasympathetic activation
sympathetics enhance inward pacemaker current ____ than they do in the sinus node
more
parasympathetics don’t work on ventricular rhythms, but
they can work on atrial tachycardia
who can change stroke volume?
sympathetics, increase SV. Paras don’t affect ventricular muscle
what can weaken contractions but act of the atria only?
Ach.
Cardiac output equation
CO = SV * HR
blood pressure equation
BP = SV *TPR
mean arterial pressure equation
CO * TPR
systolic PP
during contraction
diastolic PP
during relaxation