Flashcards in ANS Drugs Deck (61)
Transmitters released at ANS synapses
Which ANS synapses release acetylcholine
All preganglionic neurons
All parasympathetic postganglionic neurons
A few sympathetic postganglionic neurons
Which ANS synapses release NE
Most sympathetic neurons
Which ANS synpases release dopamine
Sympathetic fibers that innervate the renal vasculature and some other vessel beds
What is the predominant tone of the heart?
Different types of nicotinic receptor?
Neuronal -- the one at the ans ganglia
Muscular -- the one at the NMJ
Different types of muscarinic receptor
M2 M4 are coupled to Gi and Go
M1, 3, 5 are coupled to Gq
These activate PLC, which cleave DAG and IP3, which cause Ca release and stimulate PKC
A1 receptor cascade
Coupled to Gq. Elevate intracellular Ca 2 and stimulate protein kinase C. Contract smooth muscles. Also cause miosis.
Where do B1 receptors predominate
In the heart and in JG cells
Where do B2 receptors predominate?
In the vasculature, in bronchial smooth muscle.
Mediate vasodilation and bronchodilation
Where are Dopamine receptors
Prominent on the renal vasculature and mediate vascodilation
How is EPI/NE released from adrenals?
Behaves with a sympathetic ganglion. ACh released to adrenals, Adrenals release NE and EPI.
Baroreceptors sense decrease/increase in BP, change heart rate to match .
Sympathetic activity effect on the vasculature
Net increase in total peripheral resistance, decrease in venous capacitance.
Where do beta receptors predominate in the vasculature.
Coronaries and skeletal muscles (where needed during sympathetic outflow).
Why is renal function preserved in flight/flight?
Because DA released in sympathetic outflow on renal vasculature causes vasodilation
Effects of sympathetic activity on the heart
Mediated by B1 receptors in ventricles and B2 receptors in the atria/sa node. Positive chronotropy, positive inotropy, positive lusitrophy
How does B stimulation increase chronotropy
Increases cAMP, which increases activity of funny current. Drives to threshold quicker
What is the channel that opposes the funny current?
How does B stimulation increase AV nodal propagation?
Because cAMP activates PKA, which phosphorylates L-type Ca channels, causing them to open and allow more Ca out. More rapid action potential and faster propagation.
How does B stimulation increase inotropy and lusitropy?
P the phospholamban. Higher ca in er. More available for release, pushed out of cell quickly.
Epinephrine acts on... and causes...
B1, B2, B3, A1, A2 agonist
At high doses causes vasoconstriction (increases mean BP) and increases HR. Direct effects predominate over reflex
At low doses, diastolic BP is decreased because it is more potent at B2 than A1.
Epinephrine at low doses
Decreases diastolic BP because epinephrine has great activity at B2 relative to A2. So will dilate.. ya know?
Uses for epi
Cardiac arrest, inotropic support.
Acute asthma, analphylaxis.
Prolong action of local anesthetic because causes vasoconstriciton at high doses
A1, A2, B1
(no activity at B2)
Increases BP more than Epi.
DECREASES heart rate due to strong pressor effect.
Inotropic effect is still intact.
Uses of NE
Adverse effects of NE
Severe hypertension, reduced renal flow.
Necrosis and tissue sloughing after IV injection due to extravasation of the drug (look for blanching)!
B1, B2, B3 agonist.
Potent vasodilator (B2).
Increases HR substantially reflex is in same direction as direct, inotropy. Decreases both diastolic and MAP.
Decreases or slightly increases systolic pressure.
Uses of isoproterenol
Treatment of bradycardia in heart transplant patients.
Can treat some arrhythmias (torsades)